diff --git a/Codeforces Round 1050 (Div. 4)/D. Destruction of the Dandelion Fields.cpp b/Codeforces Round 1050 (Div. 4)/D. Destruction of the Dandelion Fields.cpp
new file mode 100644
index 0000000..e789bc9
--- /dev/null
+++ b/Codeforces Round 1050 (Div. 4)/D. Destruction of the Dandelion Fields.cpp	
@@ -0,0 +1,124 @@
+/* Problem URL: https://codeforces.com/contest/2148/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        vl even;
+        vl odd;
+
+        while (n--) {
+            ll now;
+            cin >> now;
+
+            if (now & 1) {
+                odd.push_back(now);
+            } else {
+                even.push_back(now);
+            }
+        }
+
+        if (odd.empty()) {
+            cout << "0\n";
+            continue;
+        }
+
+        sortv(odd);
+
+        ll ans = odd.back() + accumulate(all(even), 0LL);
+        odd.pop_back();
+
+        int i = 0;
+        int j = odd.size() - 1;
+
+        while (i < j) {
+            ans += odd[j];
+            i++;
+            j--;
+        }
+
+        cout << ans << '\n';
+    }
+}
diff --git a/Codeforces Round 1050 (Div. 4)/E. Split.cpp b/Codeforces Round 1050 (Div. 4)/E. Split.cpp
new file mode 100644
index 0000000..a0cef31
--- /dev/null
+++ b/Codeforces Round 1050 (Div. 4)/E. Split.cpp	
@@ -0,0 +1,133 @@
+/* Problem URL: https://codeforces.com/contest/2148/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n, k;
+        cin >> n >> k;
+
+        vi fds(n);
+        cin >> fds;
+
+        vi ncount(n + 1);
+        repv(i, fds) {
+            ncount[i]++;
+        }
+
+        vi lim(n + 1);
+
+        auto check = [&]() {
+            rep(i, n + 1) {
+                if (ncount[i] % k != 0) {
+                    return false;
+                }
+                lim[i] = ncount[i] / k;
+            }
+            return true;
+        };
+
+        if (!check()) {
+            cout << "0\n";
+            continue;
+        }
+
+        vi now(n + 1);
+
+        int l = 0;
+        int r = 0;
+        ll ans = 0;
+        while (r < n) {
+            now[fds[r]]++;
+
+            while (l < r && now[fds[r]] > lim[fds[r]]) {
+                now[fds[l]]--;
+                l++;
+            }
+
+            ans += r - l + 1;
+            r++;
+        }
+
+        cout << ans << '\n';
+    }
+}
diff --git a/Codeforces Round 1051 (Div. 2)/A. All Lengths Subtraction.cpp b/Codeforces Round 1051 (Div. 2)/A. All Lengths Subtraction.cpp
new file mode 100644
index 0000000..0702c8c
--- /dev/null
+++ b/Codeforces Round 1051 (Div. 2)/A. All Lengths Subtraction.cpp	
@@ -0,0 +1,123 @@
+/* Problem URL: https://codeforces.com/contest/2143/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        vi fds(n);
+        cin >> fds;
+
+        int now = n;
+
+        int act = 0;
+        while (fds[act] != now) {
+            act++;
+        }
+
+        int i = act;
+        int j = act;
+
+        bool pos = true;
+
+        rep(k, n - 1) {
+            if (i > 0 && fds[i - 1] == now - 1) {
+                now--;
+                i--;
+                continue;
+            }
+
+            if (j < n - 1 && fds[j + 1] == now - 1) {
+                now--;
+                j++;
+                continue;
+            }
+            
+            pos = false;
+            break;
+        }
+
+        cout << (pos ? "YES\n" : "NO\n");
+    }
+}
diff --git a/Codeforces Round 1051 (Div. 2)/B. Discounts.cpp b/Codeforces Round 1051 (Div. 2)/B. Discounts.cpp
new file mode 100644
index 0000000..610fc84
--- /dev/null
+++ b/Codeforces Round 1051 (Div. 2)/B. Discounts.cpp	
@@ -0,0 +1,130 @@
+/* Problem URL: https://codeforces.com/contest/2143/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        ll n, k;
+        cin >> n >> k;
+
+        vl a(n);
+        cin >> a;
+
+        vl b(k);
+        cin >> b;
+
+        sort(all(a), greater<>());
+        sortv(b);
+
+        ll total = 0;
+        int i = 0;
+        int now = 0;
+
+        while (i < n && now < k) {
+            int size = n - i;
+            if (b[now] > size) {
+                while (i < n) {
+                    total += a[i];
+                    i++;
+                }
+
+                break;
+            }
+
+            int lim = i + b[now] - 1;
+            while (i < lim) {
+                total += a[i];
+                i++;
+            }
+
+            i++;
+            now++;
+        }
+
+        while (i < n) {
+            total += a[i];
+            i++;
+        }
+
+        cout << total << '\n';
+    }
+}
diff --git a/Codeforces Round 1051 (Div. 2)/C. Max Tree.cpp b/Codeforces Round 1051 (Div. 2)/C. Max Tree.cpp
new file mode 100644
index 0000000..28d4801
--- /dev/null
+++ b/Codeforces Round 1051 (Div. 2)/C. Max Tree.cpp	
@@ -0,0 +1,159 @@
+/* Problem URL: https://codeforces.com/contest/2143/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        V<V<tuple<int, ll, ll>>> graph(n);
+
+        rep(i, n - 1) {
+            int u, v;
+            ll x, y;
+            cin >> u >> v >> x >> y;
+
+            if (u > v) {
+                swap(u, v);
+            }
+
+            u--, v--;
+
+            graph[u].emplace_back(v, x, y);
+            graph[v].emplace_back(u, 0, 0);
+        }
+
+        vvi newgraph(n);
+
+        function<void(int, int)> dfs = [&](int i, int p) {
+            for (auto [j, x, y] : graph[i]) {
+                if (i < j) {
+                    if (x > y) {
+                        newgraph[i].push_back(j);
+                        continue;
+                    }
+                    if (y > x) {
+                        newgraph[j].push_back(i);
+                    }
+                }
+
+                if (j == p) {
+                    continue;
+                }
+
+                dfs(j, i);
+            }
+        };
+
+        dfs(0, 0);
+
+        int now = 1;
+        vi act(n);
+
+        V<bool> vis(n);
+
+        function<void(int)> getans = [&](int i) {
+            vis[i] = true;
+
+            for (auto j : newgraph[i]) {
+                if (vis[j]) {
+                    continue;
+                }
+                getans(j);
+            }
+
+            act[i] = now;
+            now++;
+        };
+
+        rep(i, n) {
+            if (vis[i]) {
+                continue;
+            }
+
+            getans(i);
+        }
+
+        cout << act;
+    }
+}
diff --git a/Codeforces Round 1051 (Div. 2)/D1. Inversion Graph Coloring (Easy Version).cpp b/Codeforces Round 1051 (Div. 2)/D1. Inversion Graph Coloring (Easy Version).cpp
new file mode 100644
index 0000000..a6509ac
--- /dev/null
+++ b/Codeforces Round 1051 (Div. 2)/D1. Inversion Graph Coloring (Easy Version).cpp	
@@ -0,0 +1,127 @@
+/* Problem URL: https://codeforces.com/contest/2143/problem/D1 */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        vi a(n);
+        cin >> a;
+
+        ll mod = 1e9 + 7;
+
+        vvvl memo(n, vvl(n + 1, vl(n + 1, -1)));
+
+        function<ll(int, int, int)> dp = [&](int i, int maximal, int mp) {
+            if (i >= n) {
+                return 1LL;
+            }
+
+            ll &ans = memo[i][maximal][mp];
+            if (ans != -1) {
+                return ans;
+            }
+
+            ans = dp(i + 1, maximal, mp);
+
+            if (a[i] < maximal && a[i] < mp) {
+                return ans;
+            }
+
+            if (a[i] >= maximal) {
+                ans += dp(i + 1, a[i], mp);
+                ans %= mod;
+            }
+
+            if (a[i] < maximal) {
+                ans += dp(i + 1, maximal, max(mp, a[i]));
+                ans %= mod;
+            }
+
+            return ans;
+        };
+
+        cout << dp(0, 0, 0) << '\n';
+    }
+}
diff --git a/Codeforces Round 1051 (Div. 2)/E. Make Good.cpp b/Codeforces Round 1051 (Div. 2)/E. Make Good.cpp
new file mode 100644
index 0000000..b14086f
--- /dev/null
+++ b/Codeforces Round 1051 (Div. 2)/E. Make Good.cpp	
@@ -0,0 +1,133 @@
+/* Problem URL: https://codeforces.com/contest/2143/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        string par;
+        cin >> par;
+
+        if (n & 1) {
+            cout << "-1\n";
+            continue;
+        }
+
+        vi count(2);
+        repv(i, par) {
+            count[i == ')']++;
+        }
+
+        if (abs(count[0] - count[1]) % 4 != 0) {
+            cout << "-1\n";
+            continue;
+        }
+
+        string fds;
+        int c = 0;
+
+        repv(i, par) {
+            fds += i;
+
+            if (fds.size() > 1 && fds[fds.size() - 1] == fds[fds.size() - 2]) {
+                fds.pop_back();
+                fds.pop_back();
+                c++;
+            }
+        }
+
+        if (!fds.empty() && (fds.back() == '(') && c == 0) {
+            cout << "-1\n";
+            continue;
+        }
+
+        if (c) {
+            fds = "((" + fds + "))";
+            c -= 2;
+        }
+
+        fds = string(c, '(') + fds + string(c, ')');
+        cout << fds << '\n';
+    }
+}
diff --git a/Codeforces Round 1052 (Div. 2)/A. Equal Occurrences.cpp b/Codeforces Round 1052 (Div. 2)/A. Equal Occurrences.cpp
new file mode 100644
index 0000000..547c40f
--- /dev/null
+++ b/Codeforces Round 1052 (Div. 2)/A. Equal Occurrences.cpp	
@@ -0,0 +1,113 @@
+/* Problem URL: https://codeforces.com/contest/2146/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+        vi a(n);
+        cin >> a;
+
+        vi fds(n + 1);
+        repv(i, a) {
+            fds[i]++;
+        }
+
+        int ans = 0;
+        
+
+        rep(i, n + 1) {
+            int now = 0;
+
+            rep(j, n + 1) {
+                if (fds[j] >= i) {
+                    now += i;
+                }
+            }
+
+            rmax(ans, now);
+        }
+
+        cout << ans << '\n';
+    }
+}
diff --git a/Codeforces Round 1052 (Div. 2)/B. Merging the Sets.cpp b/Codeforces Round 1052 (Div. 2)/B. Merging the Sets.cpp
new file mode 100644
index 0000000..f37d228
--- /dev/null
+++ b/Codeforces Round 1052 (Div. 2)/B. Merging the Sets.cpp	
@@ -0,0 +1,127 @@
+/* Problem URL: https://codeforces.com/contest/2146/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n, m;
+        cin >> n >> m;
+
+        vi count(m);
+        vvi them(n);
+
+        int c = 0;
+
+        rep(i, n) {
+            int l;
+            cin >> l;
+
+            while (l--) {
+                int a;
+                cin >> a;
+                count[a - 1]++;
+                them[i].push_back(a - 1);
+            }
+        }
+
+        if (*min_element(all(count)) <= 0) {
+            cout << "NO\n";
+            continue;
+        }
+
+        rep(i, n) {
+            bool pos = true;
+            repv(j, them[i]) {
+                if (count[j] == 1) {
+                    pos = false;
+                    break;
+                }
+            }
+
+            if (pos) {
+                c++;
+            }
+        }
+
+        cout << (c >= 2 ? "YES\n" : "NO\n");
+    }
+}
diff --git a/Codeforces Round 1052 (Div. 2)/C. Wrong Binary Search.cpp b/Codeforces Round 1052 (Div. 2)/C. Wrong Binary Search.cpp
new file mode 100644
index 0000000..5a56ecb
--- /dev/null
+++ b/Codeforces Round 1052 (Div. 2)/C. Wrong Binary Search.cpp	
@@ -0,0 +1,136 @@
+/* Problem URL: https://codeforces.com/contest/2146/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        string a;
+        cin >> a;
+
+        vi perm(n, -1);
+        int c = 0;
+        bool pos = true;
+        
+        rep(i, n) {
+            if (a[i] == '1') {
+                perm[i] = i + 1;
+                c++;
+                continue;
+            }
+
+            if ((i == 0 || a[i - 1] == '1') && (i == n - 1 || a[i + 1] == '1')) {
+                pos = false;
+                break;
+            }
+        }
+
+        if (!pos) {
+            cout << "NO\n";
+            continue;
+        }
+
+        int i = 0;
+        int now = 0;
+
+        while (i < n) {
+            while (i < n && a[i] == '0') {
+                i++;
+            }
+
+            int tmp = i - 1;
+            while (tmp >= 0 && a[tmp] == '0') {
+                perm[tmp] = now + 1;
+                tmp--;
+                now++;
+            }
+
+            now++;
+            i++;
+        }
+
+        cout << "YES\n";
+        cout << perm;
+    }
+}
diff --git a/Codeforces Round 1052 (Div. 2)/D1. Max Sum OR (Easy Version).cpp b/Codeforces Round 1052 (Div. 2)/D1. Max Sum OR (Easy Version).cpp
new file mode 100644
index 0000000..46fdfcd
--- /dev/null
+++ b/Codeforces Round 1052 (Div. 2)/D1. Max Sum OR (Easy Version).cpp	
@@ -0,0 +1,154 @@
+/* Problem URL: https://codeforces.com/contest/2146/problem/D1 */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int l, r;
+        cin >> l >> r;
+
+        if (r == 0) {
+            cout << "0\n0\n";
+            continue;
+        }
+
+        int n = r + 1;
+
+        vi perm(n, -1);
+
+        set<int> all;
+        rep(i, n) {
+            all.insert(i);
+        }
+
+        int log = 32 - __builtin_clz(r);
+        // cout << log << '\n';
+
+        int now = r;
+        rep(i, n) {
+            if (perm[now] != -1) {
+                now--;
+                continue;
+            }
+
+            int act = 0;
+            rep(j, log) {
+                if (!((now >> j) & 1)) {
+                    act |= 1 << j;
+                }
+            }
+
+            while (act > 0 && !all.count(act)) {
+                act -= 1 << (31 - __builtin_clz(act));
+            }
+
+            if (!all.count(act)) {
+                now--;
+                continue;
+            }
+
+            // cout << now << ' ' << act << '\n';
+
+            perm[now] = act;
+            perm[act] = now;
+            all.erase(now);
+            all.erase(act);
+            now--;
+        }
+
+        rep(i, n) {
+            if (perm[i] != -1) {
+                continue;
+            }
+
+            perm[i] = *prev(all.end());
+            all.erase(prev(all.end()));
+        }
+
+        ll total = 0;
+        rep(i, n) {
+            total += perm[i] | i;
+        }
+        cout << total << '\n';
+        cout << perm;
+    }
+}
diff --git a/Codeforces Round 1052 (Div. 2)/D2. Max Sum OR (Hard Version).cpp b/Codeforces Round 1052 (Div. 2)/D2. Max Sum OR (Hard Version).cpp
new file mode 100644
index 0000000..77a8d59
--- /dev/null
+++ b/Codeforces Round 1052 (Div. 2)/D2. Max Sum OR (Hard Version).cpp	
@@ -0,0 +1,155 @@
+/* Problem URL: https://codeforces.com/contest/2146/problem/D2 */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        V<array<int, 2>> trie(1);
+        V<array<int, 2>> count(1);
+
+        auto add = [&](ll num) {
+            int now = 0;
+            rep(i, 31) {
+                int bit = (num >> i) & 1;
+                count[now][bit]++;
+                if (trie[now][bit] == 0) {
+                    trie[now][bit] = trie.size();
+                    count.emplace_back();
+                    trie.emplace_back();
+                }
+
+                now = trie[now][bit];
+            }
+        };
+
+        auto rem = [&](ll num) {
+            int now = 0;
+            rep(i, 31) {
+                int bit = (num >> i) & 1;
+                count[now][bit]--;
+                now = trie[now][bit];
+            }
+        };
+
+        ll l, r;
+        cin >> l >> r;
+
+        nrep(i, l, r + 1) {
+            add(i);
+        }
+
+        int n = r - l + 1;
+        vl ans(n);
+
+        for (int i = r; i >= l; i--) {
+            ll tmp = 0;
+            function<void(int, int)> find = [&](ll now, int j) {
+                if (j > 30) {
+                    return;
+                }
+
+                int bit = (i >> j) & 1;
+                if (count[now][bit^1] == 0) {
+                    tmp |= (bit << j);
+                    find(trie[now][bit], j + 1);
+                    return;
+                }
+
+                tmp |= ((bit^1) << j);
+                find(trie[now][bit^1], j + 1);
+            };
+
+            find(0, 0);
+
+            rem(tmp);
+            ans[i - l] = tmp;
+        }
+
+        ll total = 0;
+        rep(i, n) {
+            total += ans[i] | (i + l);
+        }
+
+        cout << total << '\n';
+        cout << ans;
+    }
+}
diff --git a/Codeforces Round 1052 (Div. 2)/E. Yet Another MEX Problem.cpp b/Codeforces Round 1052 (Div. 2)/E. Yet Another MEX Problem.cpp
new file mode 100644
index 0000000..50a3084
--- /dev/null
+++ b/Codeforces Round 1052 (Div. 2)/E. Yet Another MEX Problem.cpp	
@@ -0,0 +1,184 @@
+/* Problem URL: https://codeforces.com/contest/2146/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        vi fds(n);
+        cin >> fds;
+
+        int prev = n;
+        n++;
+        fds.push_back(0);
+        
+        while (__builtin_popcount(n) != 1) {
+            n++;
+            fds.push_back(0);
+        }
+        
+        vvi segm(n * 2);
+
+        function<void(int, int, int)> build = [&](int i, int l, int r) {
+            if (l == r) {
+                segm[i] = {fds[i - n]};
+                return;
+            }
+
+            int mid = (l + r) >> 1;
+
+            build(i * 2, l, mid);
+            build(i * 2 + 1, mid + 1, r);
+
+            merge(all(segm[i * 2]), all(segm[i * 2 + 1]), back_inserter(segm[i]));
+        };
+
+        build(1, 0, n - 1);
+
+        function<int(int, int, int, int, int, int)> querym = [&](int i, int l, int r, int tl, int tr, int v) {
+            if (l > tr || r < tl) {
+                return 0;
+            }
+
+            if (l >= tl && r <= tr) {
+                auto upper = upper_bound(all(segm[i]), v);
+                return (int)(segm[i].end() - upper);
+            }
+
+            int mid = (l + r) >> 1;
+
+            return querym(i * 2, l, mid, tl, tr, v) + querym(i * 2 + 1, mid + 1, r, tl, tr, v);
+        };
+
+        vi seg(n * 2, -1);
+
+        auto update = [&](int i, int v) {
+            i += n;
+            seg[i] = v;
+
+            for (i >>= 1; i > 0; i >>= 1) {
+                seg[i] = min(seg[i * 2], seg[i * 2 + 1]);
+            }
+        };
+        
+        function<int(int, int, int, int, int)> query = [&](int i, int l, int r, int tl, int tr) {
+            int oo = INT32_MAX >> 1;
+            if (l > tr || r < tl) {
+                return oo;
+            }
+
+            if (l >= tl && r <= tr) {
+                return seg[i];
+            }
+
+            int mid = (l + r) >> 1;
+
+            return min(query(i * 2, l, mid, tl, tr), query(i * 2 + 1, mid + 1, r, tl, tr));
+        };
+
+        vi ans(prev);
+        rep(i, prev) {
+            update(fds[i], i);
+
+            int mex = 0;
+            int ans = 0;
+
+            while (mex <= n) {
+                int minimal = query(1, 0, n - 1, 0, mex);
+
+                int tmp = querym(1, 0 , n - 1, minimal, i, mex);
+
+                if (tmp >= ans) {
+                    ans = tmp;
+                    mex++;
+                    continue;
+                }
+
+                break;
+            }
+
+            cout << ans << " \n"[i == prev - 1];
+        }
+    }
+}
diff --git a/Codeforces Round 1053 (Div. 2)/A. Incremental Subarray.cpp b/Codeforces Round 1053 (Div. 2)/A. Incremental Subarray.cpp
new file mode 100644
index 0000000..b9e3b52
--- /dev/null
+++ b/Codeforces Round 1053 (Div. 2)/A. Incremental Subarray.cpp	
@@ -0,0 +1,104 @@
+/* Problem URL: https://codeforces.com/contest/2151/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n, m;
+        cin >> n >> m;
+
+        vi fds(m);
+        cin >> fds;
+
+        auto getans = [&]() {
+            for (int i = m - 1; i > 0; i--) {
+                if (fds[i] <= fds[i - 1]) {
+                    return 1;
+                }
+            }
+
+            return n - fds.back() + 1;
+        };
+
+        cout << getans() << '\n';
+    }
+}
diff --git a/Codeforces Round 1053 (Div. 2)/B. Incremental Path.cpp b/Codeforces Round 1053 (Div. 2)/B. Incremental Path.cpp
new file mode 100644
index 0000000..ba56979
--- /dev/null
+++ b/Codeforces Round 1053 (Div. 2)/B. Incremental Path.cpp	
@@ -0,0 +1,151 @@
+/* Problem URL: https://codeforces.com/contest/2151/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n, m;
+        cin >> n >> m;
+
+        int lim = 100 * n;
+
+        V<bool> black(lim);
+        string op;
+        cin >> op;
+
+        set<int> rem;
+
+        while (m--) {
+            int now;
+            cin >> now;
+
+            if (now > lim) {
+                rem.insert(now);
+                continue;
+            }
+
+            black[now - 1] = true;
+        }
+
+        int now = 0;
+        rep(i, n) {
+            now++;
+            if (op[i] == 'A') {
+                black[now] = true;
+                continue;
+            }
+
+            int prev = now;
+            while (black[now]) {
+                now++;
+            }
+
+            black[now] = true;
+
+            if (black[prev]) {
+                while (black[now]) {
+                    now++;
+                }
+                continue;
+            }
+
+            now = prev;
+            now--;
+        }
+
+        vi ans;
+        rep(i, lim) {
+            if (black[i]) {
+                ans.push_back(i + 1);
+            }
+        }
+
+        cout << ans.size() + rem.size() << '\n';
+        repv(i, ans) {
+            cout << i << ' ';
+        }
+        repv(i, rem) {
+            cout << i << ' ';
+        }
+        cout << '\n';
+    }
+}
diff --git a/Codeforces Round 1053 (Div. 2)/C. Incremental Stay.cpp b/Codeforces Round 1053 (Div. 2)/C. Incremental Stay.cpp
new file mode 100644
index 0000000..9150ecf
--- /dev/null
+++ b/Codeforces Round 1053 (Div. 2)/C. Incremental Stay.cpp	
@@ -0,0 +1,109 @@
+/* Problem URL: https://codeforces.com/contest/2151/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+        n <<= 1;
+
+        vl fds(n);
+        cin >> fds;
+
+        vl count(2);
+
+        for (int i = 0; i < n; i += 2) {
+            count[0] += fds[i];
+            count[1] += fds[i + 1];
+        }
+
+        ll ans = 0;
+        rep(k, n >> 1) {
+            cout << count[(k & 1) ^ 1] - count[k & 1] + ans << ' ';
+            count[k & 1] -= fds[k];
+            count[(k & 1) ^ 1] -= fds[n - k - 1];
+            ans += fds[n - k - 1] - fds[k];
+        }
+        cout << '\n';
+    }
+}
diff --git a/Codeforces Round 1053 (Div. 2)/D. Grid Counting.cpp b/Codeforces Round 1053 (Div. 2)/D. Grid Counting.cpp
new file mode 100644
index 0000000..db1612a
--- /dev/null
+++ b/Codeforces Round 1053 (Div. 2)/D. Grid Counting.cpp	
@@ -0,0 +1,156 @@
+/* Problem URL: https://codeforces.com/contest/2151/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    const ll mod = 998244353;
+    vl fact(2e5 + 1);
+    vl inv(2e5 + 1);
+
+    fact[0] = 1;
+    fact[1] = 1;
+
+    nrep(i, 2, 2e5 + 1) {
+        fact[i] = (fact[i - 1] * i) % mod;
+    }
+
+    auto fpow = [&](ll a, ll p) {
+        ll ans = 1;
+        rep(i, 30) {
+            if ((p >> i) & 1) {
+                ans *= a;
+                ans %= mod;
+            }
+
+            a *= a;
+            a %= mod;
+        }
+
+        return ans;
+    };
+
+    auto comb = [&](ll n, ll k) {
+        return (fact[n] * fpow((fact[k] * fact[n - k]) % mod, mod - 2)) % mod;
+    };
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+        vi count(n);
+        cin >> count;
+
+        vi lim(n);
+        rep(i, n >> 1) {
+            lim[i] = 2;
+        }
+
+        if (n & 1) {
+            lim[n >> 1] = 1;
+        }
+
+        auto getans = [&]() {
+            if (accumulate(all(count), 0LL) != n) {
+                return 0LL;
+            }
+
+            ll ans = 1;
+
+            int total = 0;
+            for (int i = n - 1; i >= 0; i--) {
+                int c = lim[i];
+                total += c;
+
+                if (total < count[i]) {
+                    return 0LL;
+                }
+
+                ans *= comb(total, count[i]);
+                ans %= mod;
+                total -= count[i];
+            }
+
+            return ans;
+        };
+
+        cout << getans() << '\n';
+    }
+}
diff --git a/Codeforces Round 1054 (Div. 3)/A. Be Positive.cpp b/Codeforces Round 1054 (Div. 3)/A. Be Positive.cpp
new file mode 100644
index 0000000..1157e95
--- /dev/null
+++ b/Codeforces Round 1054 (Div. 3)/A. Be Positive.cpp	
@@ -0,0 +1,112 @@
+/* Problem URL: https://codeforces.com/contest/2149/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        vl fds(n);
+        cin >> fds;
+        sortv(fds);
+
+        ll ans = 0;
+        int neg = 0;
+        rep(i, n) {
+            if (fds[i] == 0) {
+                ans++;
+                continue;
+            }
+
+            if (fds[i] < 0) {
+                neg++;
+            }
+        }
+
+        if (neg & 1) {
+            ans += -fds[0] + 1;
+        }
+
+        cout << ans << '\n';
+    }
+}
diff --git a/Codeforces Round 1054 (Div. 3)/B. Unconventional Pairs.cpp b/Codeforces Round 1054 (Div. 3)/B. Unconventional Pairs.cpp
new file mode 100644
index 0000000..7d20bb1
--- /dev/null
+++ b/Codeforces Round 1054 (Div. 3)/B. Unconventional Pairs.cpp	
@@ -0,0 +1,99 @@
+/* Problem URL: https://codeforces.com/contest/2149/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+        vi fds(n);
+        cin >> fds;
+        sortv(fds);
+
+        int ans = 0;
+        for (int i = 0; i < n; i += 2) {
+            rmax(ans, fds[i + 1] - fds[i]);
+        }
+
+        cout << ans << '\n';
+    }
+}
diff --git a/Codeforces Round 1054 (Div. 3)/C. MEX rose.cpp b/Codeforces Round 1054 (Div. 3)/C. MEX rose.cpp
new file mode 100644
index 0000000..aad898b
--- /dev/null
+++ b/Codeforces Round 1054 (Div. 3)/C. MEX rose.cpp	
@@ -0,0 +1,108 @@
+/* Problem URL: https://codeforces.com/contest/2149/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n, k;
+        cin >> n >> k;
+
+        vi count(n + 1);
+        rep(i, n) {
+            int n;
+            cin >> n;
+            count[n]++;
+        }
+
+        int ans = 0;
+        int add = 0;
+        rep(i, k) {
+            if (count[i] == 0) {
+                add++;
+                ans++;
+            }
+        }
+
+        ans += max(0, count[k] - add);
+        cout << ans << '\n';
+    }
+}
diff --git a/Codeforces Round 1054 (Div. 3)/D. A and B.cpp b/Codeforces Round 1054 (Div. 3)/D. A and B.cpp
new file mode 100644
index 0000000..c773fca
--- /dev/null
+++ b/Codeforces Round 1054 (Div. 3)/D. A and B.cpp	
@@ -0,0 +1,152 @@
+/* Problem URL: https://codeforces.com/contest/2149/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        string a;
+        cin >> a;
+
+        vi act(n);
+        rep(i, n) {
+            act[i] = a[i] - 'a';
+        }
+
+        vl apref(n + 1);
+        vl asuf(n + 1);
+        vl bpref(n + 1);
+        vl bsuf(n + 1);
+
+        int c = 0;
+        rep(i, n) {
+            apref[i + 1] = apref[i];
+            if (act[i]) {
+                apref[i + 1] += i - c;
+                c++;
+            }
+        }
+
+        c = 0;
+        for (int i = n - 1; i >= 0; i--) {
+            asuf[i] = asuf[i + 1];
+            if (act[i]) {
+                asuf[i] += n - i - 1 - c;
+                c++;
+            }
+        }
+
+        c = 0;
+        rep(i, n) {
+            bpref[i + 1] = bpref[i];
+            if (!act[i]) {
+                bpref[i + 1] += i - c;
+                c++;
+            }
+        }
+
+        c = 0;
+        for (int i = n - 1; i >= 0; i--) {
+            bsuf[i] = bsuf[i + 1];
+            if (!act[i]) {
+                bsuf[i] += n - i - c - 1;
+                c++;
+            }
+        }
+
+
+        ll ans = INT64_MAX >> 1;
+
+        rep(i, n) {
+            if (act[i]) {
+                rmin(ans, bpref[i] + bsuf[i + 1]);
+                continue;
+            }
+
+            rmin(ans, apref[i] + asuf[i + 1]);
+        }
+
+        cout << ans << '\n';
+    }
+}
diff --git a/Codeforces Round 1054 (Div. 3)/E. Hidden Knowledge of the Ancients.cpp b/Codeforces Round 1054 (Div. 3)/E. Hidden Knowledge of the Ancients.cpp
new file mode 100644
index 0000000..79c63dd
--- /dev/null
+++ b/Codeforces Round 1054 (Div. 3)/E. Hidden Knowledge of the Ancients.cpp	
@@ -0,0 +1,175 @@
+/* Problem URL: https://codeforces.com/contest/2149/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n, k, l, r;
+        cin >> n >> k >> l >> r;
+
+        map<int, int> var;
+        vi fds(n);
+        repv(i, fds) {
+            cin >> i;
+            var[i] = 0;
+        }
+
+        int v = 0;
+        repv(i, var) {
+            i.second = v;
+            v++;
+        }
+
+        repv(i, fds) {
+            i = var[i];
+        }
+
+        vi elem1(v);
+        vi elem2(v);
+
+        int c1 = 0;
+        int c2 = 0;
+
+        auto add = [&](vi &elem, int i, int &c) {
+            elem[i]++;
+            if (elem[i] == 1) {
+                c++;
+            }
+        };
+
+        auto rem = [&](vi &elem, int i, int &c) {
+            elem[i]--;
+            if (elem[i] == 0) {
+                c--;
+            }
+        };
+
+        int l1 = 0;
+        int l2 = 0;
+
+        rep(i, l - 1) {
+            add(elem1, fds[i], c1);
+            add(elem2, fds[i], c2);
+        }
+
+        auto reorder1 = [&](int start, int lim) {
+            while (l1 < start) {
+                rem(elem1, fds[l1], c1);
+                l1++;
+            }
+
+            while (c1 > k && l1 < lim) {
+                rem(elem1, fds[l1], c1);
+                l1++;
+            }
+        };
+
+        auto reorder2 = [&](int start, int lim) {
+            while (l2 < start) {
+                rem(elem2, fds[l2], c2);
+                l2++;
+            }
+
+            while (c2 >= k && l2 <= lim) {
+                rem(elem2, fds[l2], c2);
+                l2++;
+            }
+        };
+
+        ll ans = 0;
+
+        nrep(i, l - 1, n) {
+            add(elem1, fds[i], c1);
+            add(elem2, fds[i], c2);
+            reorder1(i - r + 1, i - l + 1);
+            reorder2(i - r + 1, i - l + 1);
+
+            if (c1 != k) {
+                continue;
+            }
+
+            ans += l2 - l1;
+        }
+
+        cout << ans << '\n';
+    }
+}
diff --git a/Codeforces Round 1054 (Div. 3)/F. Nezuko in the Clearing.cpp b/Codeforces Round 1054 (Div. 3)/F. Nezuko in the Clearing.cpp
new file mode 100644
index 0000000..0d177c4
--- /dev/null
+++ b/Codeforces Round 1054 (Div. 3)/F. Nezuko in the Clearing.cpp	
@@ -0,0 +1,118 @@
+/* Problem URL: https://codeforces.com/contest/2149/problem/F */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        ll h, d;
+        cin >> h >> d;
+
+        ll add = 0;
+        if (h == 1) {
+            add = 1;
+        } else {
+            h--;
+        }
+
+        ll low = 0;
+        ll high = d - 1;
+        ll ans = d;
+        while (low <= high) {
+            ll mid = (high + low) >> 1;
+
+            ll div = d / (mid + 1);
+            ll rem = d % (mid + 1);
+
+            ll tmp = (div * (div + 1) / 2) * (mid - rem + 1) + ((div + 1) * (div + 2) / 2) * rem - mid;
+
+            if (tmp <= h) {
+                ans = mid;
+                high = mid - 1;
+                continue;
+            }
+
+            low = mid + 1;
+        };
+
+        cout << ans + d + add << '\n';
+    }
+}
diff --git a/Codeforces Round 1054 (Div. 3)/G. Buratsuta 3.cpp b/Codeforces Round 1054 (Div. 3)/G. Buratsuta 3.cpp
new file mode 100644
index 0000000..7c0e840
--- /dev/null
+++ b/Codeforces Round 1054 (Div. 3)/G. Buratsuta 3.cpp	
@@ -0,0 +1,144 @@
+/* Problem URL: https://codeforces.com/contest/2149/problem/G */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    mt19937 seed(chrono::steady_clock::now().time_since_epoch().count());
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n, q;
+        cin >> n >> q;
+
+        vl fds(n);
+
+        map<ll, int> var;
+        repv(i, fds) {
+            cin >> i;
+            var[i] = 0;
+        }
+
+        int v = 0;
+        vi inv(var.size());
+        repv(i, var) {
+            i.second = v;
+            inv[v] = i.first;
+            v++;
+        }
+
+        vvi pos(var.size());
+
+        rep(i, n) {
+            fds[i] = var[fds[i]];
+            pos[fds[i]].push_back(i);
+        }
+
+        while (q--) {
+            set<int> ans;
+
+            int l, r;
+            cin >> l >> r;
+            l--, r--;
+
+            uniform_int_distribution<> rng(l, r);
+
+            int lim = (r - l + 1) / 3;
+
+            rep(i, 50) {
+                int now = rng(seed);
+                int count = upper_bound(all(pos[fds[now]]), r) - lower_bound(all(pos[fds[now]]), l);
+
+                if (count > lim) {
+                    ans.insert(inv[fds[now]]);
+                }
+            }
+
+            if (ans.empty()) {
+                cout << "-1\n";
+            }
+
+            repv(i, ans) {
+                cout << i << ' ';
+            }
+            cout << '\n';
+        }
+    }
+}
diff --git a/Codeforces Round 112 (Div. 2)/E. Compatible Numbers.cpp b/Codeforces Round 112 (Div. 2)/E. Compatible Numbers.cpp
new file mode 100644
index 0000000..2313552
--- /dev/null
+++ b/Codeforces Round 112 (Div. 2)/E. Compatible Numbers.cpp	
@@ -0,0 +1,118 @@
+/* Problem URL: https://codeforces.com/contest/165/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+    
+    vl fds(n);
+    cin >> fds;
+
+    const int log = 22;
+    V<bool> sos(1 << log);
+    repv(i, fds) {
+        sos[i] = true;
+    }
+
+    rep(i, log) {
+        for (int j = 0; j < (1 << log); j++) {
+            if (sos[j]) {
+                continue;
+            }
+
+            if ((j >> i) & 1) {
+                sos[j] = sos[j ^ (1 << i)];
+            }
+        }
+    }
+
+    repv(i, fds) {
+        ll now = ~i & ((1 << log) - 1);
+        rep(j, log) {
+            if (((now >> j) & 1) && sos[now ^ (1 << j)]) {
+                now ^= (1 << j);
+            }
+        }
+
+        cout << (sos[now] ? now : -1) << ' ';
+    }
+    cout << '\n';
+}
diff --git a/Codeforces Round 225 (Div. 1)/E. Vowels.cpp b/Codeforces Round 225 (Div. 1)/E. Vowels.cpp
new file mode 100644
index 0000000..43c19df
--- /dev/null
+++ b/Codeforces Round 225 (Div. 1)/E. Vowels.cpp	
@@ -0,0 +1,118 @@
+/* Problem URL: https://codeforces.com/contest/383/problem/E */
+
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    const int log = 24;
+    vl sos(1 << log);
+
+    int n;
+    cin >> n;
+    while (n--) {
+        string a;
+        cin >> a;
+
+        int mask = 0;
+
+        repv(i, a) {
+            mask |= 1 << (i - 'a');
+        }
+
+        for (int i = mask; i > 0; i = (i - 1)&mask) {
+            sos[i] += __builtin_popcount(i) & 1 ? 1 : -1;
+        }
+    }
+
+    rep(i, log) {
+        rep(j, 1 << log) {
+            if ((j >> i) & 1) {
+                sos[j] += sos[j ^ (1 << i)];
+            }
+        }
+    }
+
+    ll ans = 0;
+    rep(j, 1 << log) {
+        ans ^= sos[j] * sos[j];
+    }
+
+    cout << ans << '\n';
+}
diff --git a/Codeforces Round 271 (Div. 2)/F. Ant colony.cpp b/Codeforces Round 271 (Div. 2)/F. Ant colony.cpp
new file mode 100644
index 0000000..940139d
--- /dev/null
+++ b/Codeforces Round 271 (Div. 2)/F. Ant colony.cpp	
@@ -0,0 +1,143 @@
+/* Problem URL: https://codeforces.com/problemset/problem/474/F */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    vi fds(n);
+    cin >> fds;
+
+    vvi sparse(20, vi(n));
+
+    rep(i, n) {
+        sparse[0][i] = fds[i];
+    }
+
+    nrep(j, 1, 20) {
+        rep(i, n - (1 << (j - 1))) {
+            sparse[j][i] = __gcd(sparse[j - 1][i], sparse[j - 1][i + (1 << (j - 1))]);
+        }
+    }
+
+    auto squery = [&](int l, int r) {
+        int log = 31 - __builtin_clz(r - l + 1);
+        return __gcd(sparse[log][l], sparse[log][r - (1 << log) + 1]);
+    };
+
+    while (__builtin_popcount(n) != 1) {
+        n++;
+        fds.push_back(1);
+    }
+
+    vvi seg(n * 2);
+
+    nrep(i, n, n * 2) {
+        seg[i] = {fds[i - n]};
+    }
+
+    for (int i = n - 1; i > 0; i--) {
+        merge(all(seg[i * 2]), all(seg[i * 2 + 1]), back_inserter(seg[i]));
+    }
+
+    function<int(int, int, int, int, int, int)> query = [&](int i, int l, int r, int tl, int tr, int v) -> int {
+        if (l > tr || r < tl) {
+            return 0;
+        }
+
+        if (l >= tl && r <= tr) {
+            return upper_bound(all(seg[i]), v) - lower_bound(all(seg[i]), v);
+        }
+
+        int mid = (l + r) >> 1;
+
+        return query(i * 2, l, mid, tl, tr, v) + query(i * 2 + 1, mid + 1, r, tl, tr, v);
+    };
+
+    int q;
+    cin >> q;
+    while (q--) {
+        int l, r;
+        cin >> l >> r;
+        l--, r--;
+        cout << (r - l + 1) - query(1, 0, n - 1, l, r, squery(l, r)) << '\n';
+    }
+}
diff --git a/Educational Codeforces Round 1/A. Tricky Sum.cpp b/Educational Codeforces Round 1/A. Tricky Sum.cpp
new file mode 100644
index 0000000..07f7d18
--- /dev/null
+++ b/Educational Codeforces Round 1/A. Tricky Sum.cpp	
@@ -0,0 +1,99 @@
+/* Problem URL: https://codeforces.com/contest/598/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        ll n;
+        cin >> n;
+
+        ll ans = n * (n + 1) / 2;
+
+        ll now = 1;
+        while (now <= n) {
+            ans -= now * 2;
+            now <<= 1;
+        }
+
+        cout << ans << '\n';
+    }
+}
diff --git a/Educational Codeforces Round 1/B. Queries on a String.cpp b/Educational Codeforces Round 1/B. Queries on a String.cpp
new file mode 100644
index 0000000..2244cb5
--- /dev/null
+++ b/Educational Codeforces Round 1/B. Queries on a String.cpp	
@@ -0,0 +1,102 @@
+/* Problem URL: https://codeforces.com/contest/598/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    string s;
+    cin >> s;
+
+    int m;
+    cin >> m;
+    while (m--) {
+        int l, r, k;
+        cin >> l >> r >> k;
+        l--, r--;
+
+        k = (k - 1) % (r - l + 1) + 1;
+
+        string ans = s.substr(r - k + 1, k) + s.substr(l, (r - l + 1) - k);
+        rep(i, ans.size()) {
+            s[l + i] = ans[i];
+        }
+    }
+
+    cout << s << '\n';
+}
diff --git a/Educational Codeforces Round 1/C. Nearest vectors.cpp b/Educational Codeforces Round 1/C. Nearest vectors.cpp
new file mode 100644
index 0000000..c2ca24d
--- /dev/null
+++ b/Educational Codeforces Round 1/C. Nearest vectors.cpp	
@@ -0,0 +1,183 @@
+/* Problem URL: https://codeforces.com/contest/598/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+#define sq(x) ((x)*(ll)(x))
+
+struct pt { // ponto
+	ll x, y;
+	pt(int x_ = 0, int y_ = 0) : x(x_), y(y_) {}
+	bool operator < (const pt p) const {
+		if (x != p.x) return x < p.x;
+		return y < p.y;
+	}
+	bool operator == (const pt p) const {
+		return x == p.x and y == p.y;
+	}
+	pt operator + (const pt p) const { return pt(x+p.x, y+p.y); }
+	pt operator - (const pt p) const { return pt(x-p.x, y-p.y); }
+	pt operator * (const int c) const { return pt(x*c, y*c); }
+	ll operator * (const pt p) const { return x*(ll)p.x + y*(ll)p.y; }
+	ll operator ^ (const pt p) const { return x*(ll)p.y - y*(ll)p.x; }
+	friend istream& operator >> (istream& in, pt& p) {
+		return in >> p.x >> p.y;
+	}
+};
+
+struct line { // reta
+	pt p, q;
+	line() {}
+	line(pt p_, pt q_) : p(p_), q(q_) {}
+	friend istream& operator >> (istream& in, line& r) {
+		return in >> r.p >> r.q;
+	}
+};
+
+// PONTO & VETOR
+
+ll dist2(pt p, pt q) { // quadrado da distancia
+	return sq(p.x - q.x) + sq(p.y - q.y);
+}
+
+ll sarea2(pt p, pt q, pt r) { // 2 * area com sinal
+	return (q-p)^(r-q);
+}
+
+bool col(pt p, pt q, pt r) { // se p, q e r sao colin.
+	return sarea2(p, q, r) == 0;
+}
+
+bool ccw(pt p, pt q, pt r) { // se p, q, r sao ccw
+	return sarea2(p, q, r) > 0;
+}
+
+int quad(pt p) { // quadrante de um ponto
+	return (p.x<0)^3*(p.y<0);
+}
+
+bool compare_angle(pt p, pt q) { // retorna se ang(p) < ang(q)
+	if (quad(p) != quad(q)) return quad(p) < quad(q);
+	return ccw(q, pt(0, 0), p);
+}
+
+pt rotate90(pt p) { // rotaciona 90 graus
+	return pt(-p.y, p.x);
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    V<pair<pt, int>> fds(n);
+    rep(i, n) {
+        cin >> fds[i].first;
+        fds[i].second = i + 1;
+    }
+
+    sort(all(fds), [&](pair<pt, int> &a, pair<pt, int> &b) {
+            return compare_angle(a.first, b.first);
+         });
+
+    auto better = [&](pt &a, pt &b, pt &c, pt &d) {
+        pt p1(a * b, abs(a ^ b));
+        pt p2(c * d, abs(c ^ d));
+        return (p1 ^ p2) > 0;
+    };
+
+    int ans1 = 0;
+    int ans2 = 1;
+    nrep(i, 1, n - 1) {
+        pt &one = fds[i].first;
+        pt &two = fds[i + 1].first;
+        if (better(one, two, fds[ans1].first, fds[ans2].first)) {
+            ans1 = i;
+            ans2 = i + 1;
+        }
+    }
+
+    pt &one = fds.back().first;
+    pt &two = fds[0].first;
+    if (better(one, two, fds[ans1].first, fds[ans2].first)) {
+        ans1 = n - 1;
+        ans2 = 0;
+    }
+
+    cout << fds[ans1].second << ' ' << fds[ans2].second << '\n';
+}
diff --git a/Educational Codeforces Round 1/D. Igor In the Museum.cpp b/Educational Codeforces Round 1/D. Igor In the Museum.cpp
new file mode 100644
index 0000000..97d9ec4
--- /dev/null
+++ b/Educational Codeforces Round 1/D. Igor In the Museum.cpp	
@@ -0,0 +1,142 @@
+/* Problem URL: https://codeforces.com/contest/598/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m, k;
+    cin >> n >> m >> k;
+
+    V<string> fds(n);
+    cin >> fds;
+
+    V<V<bool>> vis(n, V<bool>(m));
+
+    function<int(int, int)> dfs = [&](int i, int j) {
+        if (fds[i][j] == '*') {
+            return 1;
+        }
+
+        vis[i][j] = true;
+
+        int ans = 0;
+
+        int add[][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
+        repv(k, add) {
+            int id = i + k[0];
+            int jd = j + k[1];
+            if (id >= 0 && id < n && jd >= 0 && jd < m && !vis[id][jd]) {
+                ans += dfs(id, jd);
+            }
+        }
+
+        return ans;
+    };
+
+    vvi ans(n, vi(m));
+
+    function<void(int, int, int)> flood = [&](int i, int j, int v) {
+        fds[i][j] = '*';
+        ans[i][j] = v;
+
+        int add[][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
+        repv(k, add) {
+            int id = i + k[0];
+            int jd = j + k[1];
+            if (id >= 0 && id < n && jd >= 0 && jd < m && fds[id][jd] == '.') {
+                flood(id, jd, v);
+            }
+        }
+    };
+
+    rep(i, n) {
+        rep(j, m) {
+            if (fds[i][j] == '.' && !vis[i][j]) {
+                int tmp = dfs(i, j);
+                flood(i, j, tmp);
+            }
+        }
+    }
+
+    while (k--) {
+        int i, j;
+        cin >> i >> j;
+        cout << ans[i - 1][j - 1] << '\n';
+    }
+}
diff --git a/Educational Codeforces Round 182 (Rated for Div. 2)/C. Non-Descending Arrays.cpp b/Educational Codeforces Round 182 (Rated for Div. 2)/C. Non-Descending Arrays.cpp
new file mode 100644
index 0000000..7d0f01d
--- /dev/null
+++ b/Educational Codeforces Round 182 (Rated for Div. 2)/C. Non-Descending Arrays.cpp	
@@ -0,0 +1,117 @@
+/* Problem URL: https://codeforces.com/contest/2144/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        cin >> n;
+
+        vi a(n);
+        vi b(n);
+        cin >> a >> b;
+
+        ll mod = 998244353;
+        vvl dp(n, vl(2));
+
+        dp[0][0] = 1;
+        dp[0][1] = 1;
+
+        nrep(i, 1, n) {
+            if (a[i] >= a[i - 1] && b[i] >= b[i - 1]) {
+                dp[i][0] += dp[i - 1][0];
+                dp[i][0] %= mod;
+                dp[i][1] += dp[i - 1][1];
+                dp[i][1] %= mod;
+            }
+
+            if (a[i] >= b[i - 1] && b[i] >= a[i - 1]) {
+                dp[i][0] += dp[i - 1][1];
+                dp[i][0] %= mod;
+                dp[i][1] += dp[i - 1][0];
+                dp[i][1] %= mod;
+            }
+        }
+
+        cout << (dp.back()[0] + dp.back()[1]) % mod << '\n';
+    }
+}
diff --git a/Educational Codeforces Round 182 (Rated for Div. 2)/D. Price Tags.cpp b/Educational Codeforces Round 182 (Rated for Div. 2)/D. Price Tags.cpp
new file mode 100644
index 0000000..f19d75d
--- /dev/null
+++ b/Educational Codeforces Round 182 (Rated for Div. 2)/D. Price Tags.cpp	
@@ -0,0 +1,115 @@
+/* Problem URL: https://codeforces.com/contest/2144/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+    cin >> t;
+    while (t--) {
+        int n;
+        ll y;
+        cin >> n >> y;
+
+        set<int> divs;
+        vl fds(n);
+        cin >> fds;
+
+        auto getdivs = [&](ll v) {
+            for (ll i = 1; i * i <= v; i++) {
+                if (v % i == 0) {
+                    divs.insert(i);
+                    divs.insert(v / i);
+                }
+            }
+        };
+
+        repv(i, fds) {
+            getdivs(i);
+        }
+
+        divs.erase(1);
+
+        ll ans = -1e17;
+
+        repv(j, divs) {
+
+        }
+    }
+}
diff --git a/Educational Codeforces Round 40 (Rated for Div. 2)/A. Diagonal Walking.cpp b/Educational Codeforces Round 40 (Rated for Div. 2)/A. Diagonal Walking.cpp
new file mode 100644
index 0000000..2afa4b8
--- /dev/null
+++ b/Educational Codeforces Round 40 (Rated for Div. 2)/A. Diagonal Walking.cpp	
@@ -0,0 +1,102 @@
+/* Problem URL: https://codeforces.com/contest/954/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    string a;
+    cin >> n >> a;
+
+    map<char, char> valid;
+    valid['U'] = 'R';
+    valid['R'] = 'U';
+
+    int ans = 0;
+
+    nrep(i, 1, n) {
+        ans++;
+        if (a[i] == valid[a[i - 1]]) {
+            a[i] = ' ';
+            ans--;
+        }
+    }
+
+    cout << ans + 1 << '\n';
+}
diff --git a/Educational Codeforces Round 40 (Rated for Div. 2)/B. String Typing.cpp b/Educational Codeforces Round 40 (Rated for Div. 2)/B. String Typing.cpp
new file mode 100644
index 0000000..5045f4d
--- /dev/null
+++ b/Educational Codeforces Round 40 (Rated for Div. 2)/B. String Typing.cpp	
@@ -0,0 +1,107 @@
+/* Problem URL: https://codeforces.com/contest/954/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    string a;
+    cin >> n >> a;
+
+    vvi dp(n, vi(2));
+    dp[0][0] = 1;
+    dp[0][1] = 1;
+
+    nrep(i, 1, n) {
+        dp[i][0] = dp[i - 1][0] + 1;
+        dp[i][1] = dp[i - 1][1] + 1;
+
+        if (!(i & 1)) {
+            continue;
+        }
+
+        int mid = i >> 1;
+
+        if (a.substr(0, mid + 1) == a.substr(mid + 1, mid + 1)) {
+            rmin(dp[i][1], dp[mid][0] + 1);
+        }
+    }
+
+    cout << min(dp[n - 1][1], dp[n - 1][0]) << '\n';
+}
diff --git a/Educational Codeforces Round 40 (Rated for Div. 2)/C. Matrix Walk.cpp b/Educational Codeforces Round 40 (Rated for Div. 2)/C. Matrix Walk.cpp
new file mode 100644
index 0000000..7f1648e
--- /dev/null
+++ b/Educational Codeforces Round 40 (Rated for Div. 2)/C. Matrix Walk.cpp	
@@ -0,0 +1,164 @@
+/* Problem URL: https://codeforces.com/contest/954/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    vl fds(n);
+    cin >> fds;
+
+    if (n == 1) {
+        cout << "YES\n";
+        cout << "1 1000000000\n";
+        return 0;
+    }
+
+    ll m = -1;
+
+    nrep(i, 1, n) {
+        if (fds[i] == fds[i - 1]) {
+            cout << "NO\n";
+            return 0;
+        }
+
+        if (abs(fds[i] - fds[i - 1]) == 1) {
+            continue;
+        }
+
+        if (m == -1) {
+            m = abs(fds[i] - fds[i - 1]);
+            continue;
+        }
+
+        if (abs(fds[i] - fds[i - 1]) != m) {
+             cout << "NO\n";
+             return 0;
+        }
+    }
+
+    if (m == -1) {
+        cout << "YES\n";
+        cout << "1 1000000000\n";
+        return 0;
+    }
+
+    ll i = (fds[0] - 1) / m;
+    ll j = (fds[0] - 1) % m;
+
+    ll nans = i + 1;
+
+    nrep(k, 1, n) {
+        if (abs(fds[k] - fds[k - 1]) == 1) {
+            ll jd = j + fds[k] - fds[k - 1];
+            ll id = i;
+
+            if (jd >= m || jd < 0) {
+                cout << "NO\n";
+                return 0;
+            }
+
+            i = id;
+            j = jd;
+            continue;
+        }
+
+        ll id = i + (fds[k] - fds[k - 1]) / m;
+        ll jd = j;
+
+        if (id < 0) {
+            cout << "NO\n";
+            return 0;
+        }
+
+        rmax(nans, id + 1);
+        i = id;
+        j = jd;
+    }
+
+    if (nans > 1e9 || m > 1e9) {
+        cout << "NO\n";
+        return 0;
+    }
+
+    cout << "YES\n";
+    cout << nans << ' ' << m << '\n';
+}
diff --git a/Educational Codeforces Round 40 (Rated for Div. 2)/D. Fight Against Traffic.cpp b/Educational Codeforces Round 40 (Rated for Div. 2)/D. Fight Against Traffic.cpp
new file mode 100644
index 0000000..30c1b22
--- /dev/null
+++ b/Educational Codeforces Round 40 (Rated for Div. 2)/D. Fight Against Traffic.cpp	
@@ -0,0 +1,152 @@
+/* Problem URL: https://codeforces.com/contest/954/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m, s, t;
+    cin >> n >> m >> s >> t;
+    s--, t--;
+
+    vvi graph(n);
+    vvi adj(n, vi(n));
+
+    while (m--) {
+        int a, b;
+        cin >> a >> b;
+        a--, b--;
+
+        graph[a].push_back(b);
+        graph[b].push_back(a);
+        adj[a][b] = 1;
+        adj[b][a] = 1;
+    }
+
+    int oo = INT32_MAX >> 1;
+
+    auto bfs = [&](int s, vi &depth){
+        depth[s] = 0;
+        queue<int> q;
+        q.push(s);
+
+        while (!q.empty()) {
+            auto i = q.front();
+            q.pop();
+
+            for (auto j : graph[i]) {
+                if (depth[j] > depth[i] + 1) {
+                    depth[j] = depth[i] + 1;
+                    q.push(j);
+                }
+            }
+        }
+    };
+
+    vi depth1(n, oo);
+    vi depth2(n, oo);
+    
+    bfs(s, depth1);
+    bfs(t, depth2);
+
+    int minimal = depth1[t];
+
+    V<bool> ispath(n);
+
+    ll ans = 0;
+    rep(i, n) {
+        nrep(j, i + 1, n) {
+            if (adj[i][j]) {
+                continue;
+            }
+
+            auto check = [&](int u, int v) {
+                int ne1 = min(depth1[u], depth1[v] + 1);
+                int ne2 = min(depth2[u], depth2[v] + 1);
+
+                return ne1 + ne2 >= minimal;
+            };
+
+            if (check(i, j) && check(j, i)) {
+                ans++;
+            }
+        }
+    }
+
+    cout << ans << '\n';
+}
diff --git a/Educational Codeforces Round 40 (Rated for Div. 2)/E. Water Taps.cpp b/Educational Codeforces Round 40 (Rated for Div. 2)/E. Water Taps.cpp
new file mode 100644
index 0000000..bb171ec
--- /dev/null
+++ b/Educational Codeforces Round 40 (Rated for Div. 2)/E. Water Taps.cpp	
@@ -0,0 +1,173 @@
+/* Problem URL: https://codeforces.com/contest/954/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    long double t;
+    cin >> n >> t;
+
+    V<pair<long double, long double>> a(n);
+    repv(i, a) {
+        cin >> i.second;
+    }
+    repv(i, a) {
+        cin >> i.first;
+    }
+
+    sort(all(a), [&](pair<long double, long double> &a, pair<long double, long double> &b) {
+            if (a.first == b.first) {
+                return a.second > b.second;
+            }
+            return a.first < b.first;
+         });
+
+    long double start = 0;
+    long double test = 0;
+    rep(i, n) {
+        start += a[i].second;
+        test += a[i].second * a[i].first;
+    }
+
+    if (test / start < t) {
+        cout << "0\n";
+        return 0;
+    }
+
+    long double low = 0;
+    long double high = start;
+    rep(i, 300) {
+        long double mid = (high + low) / 2.0L;
+
+        long double ans = 0;
+
+        long double tmp = mid;
+        long double total = 0;
+
+        rep(i, n) {
+            if (a[i].second >= tmp) {
+                ans += tmp * a[i].first;
+                total += tmp;
+                break;
+            }
+
+            ans += a[i].second * a[i].first;
+            total += a[i].second;
+            tmp -= a[i].second;
+        }
+
+        ans /= total;
+
+        // cout << high - low << ' ' << mid << ' ' << ans << '\n';
+
+        if (ans <= t) {
+            low = mid;
+            continue;
+        }
+
+        high = mid;
+    }
+
+    long double tmp = low;
+    long double total = 0;
+    long double temp = 0;
+
+    rep(i, n) {
+        if (a[i].second >= tmp) {
+            temp += tmp * a[i].first;
+            total += tmp;
+            break;
+        }
+        
+        temp += a[i].second * a[i].first;
+        total += a[i].second;
+        tmp -= a[i].second;
+    }
+
+    temp /= total;
+
+    // long double eps = 1e-9;
+    // if (abs(t - temp) >= eps) {
+    //     cout << "0\n";
+    //     return 0;
+    // }
+
+    cout << setprecision(9) << low << '\n';
+}
diff --git a/Educational Codeforces Round 41 (Rated for Div. 2)/A. Tetris.cpp b/Educational Codeforces Round 41 (Rated for Div. 2)/A. Tetris.cpp
new file mode 100644
index 0000000..e10c5e0
--- /dev/null
+++ b/Educational Codeforces Round 41 (Rated for Div. 2)/A. Tetris.cpp	
@@ -0,0 +1,95 @@
+/* Problem URL: https://codeforces.com/contest/961/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    vi fds(n);
+
+    while (m--) {
+        int a;
+        cin >> a;
+        fds[a - 1]++;
+    }
+
+    cout << *min_element(all(fds)) << '\n';
+}
diff --git a/Educational Codeforces Round 41 (Rated for Div. 2)/B. Lecture Sleep.cpp b/Educational Codeforces Round 41 (Rated for Div. 2)/B. Lecture Sleep.cpp
new file mode 100644
index 0000000..4df0622
--- /dev/null
+++ b/Educational Codeforces Round 41 (Rated for Div. 2)/B. Lecture Sleep.cpp	
@@ -0,0 +1,110 @@
+/* Problem URL: https://codeforces.com/contest/961/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, k;
+    cin >> n >> k;
+
+    vl fds(n);
+    cin >> fds;
+
+    vl aw(n);
+    cin >> aw;
+
+    ll ans = 0;
+    vl pref(n + 1);
+    vl valpref(n + 1);
+    rep(i, n) {
+        pref[i + 1] = pref[i] + fds[i];
+        valpref[i + 1] += valpref[i];
+
+        if (aw[i]) {
+            ans += fds[i];
+            valpref[i + 1] += fds[i];
+        }
+    }
+
+    rep(i, n - k + 1) {
+        rmax(ans, valpref[i] + pref[i + k] - pref[i] + valpref[n] - valpref[i + k]);
+    }
+
+    cout << ans << '\n';
+}
diff --git a/Educational Codeforces Round 41 (Rated for Div. 2)/C. Chessboard.cpp b/Educational Codeforces Round 41 (Rated for Div. 2)/C. Chessboard.cpp
new file mode 100644
index 0000000..da0b228
--- /dev/null
+++ b/Educational Codeforces Round 41 (Rated for Div. 2)/C. Chessboard.cpp	
@@ -0,0 +1,131 @@
+/* Problem URL: https://codeforces.com/contest/961/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    V<V<string>> fds(4, V<string>(n));
+
+    repv(i, fds) {
+        cin >> i;
+    }
+
+    vi perm = {0, 1, 2, 3};
+
+    int ans = INT32_MAX >> 1;
+
+    do {
+        V<string> act(2 * n);
+        rep(i, n) {
+            act[i] = fds[perm[0]][i] + fds[perm[1]][i];
+            act[i + n] = fds[perm[2]][i] + fds[perm[3]][i];
+        }
+
+        int now = 0;
+        rep(i, 2 * n) {
+            rep(j, 2 * n) {
+                if ((i + j) & 1) {
+                    now += act[i][j] == '0';
+                } else {
+                    now += act[i][j] == '1';
+                }
+            }
+        }
+
+        rmin(ans, now);
+
+        now = 0;
+        rep(i, 2 * n) {
+            rep(j, 2 * n) {
+                if ((i + j) & 1) {
+                    now += act[i][j] == '1';
+                } else {
+                    now += act[i][j] == '0';
+                }
+            }
+        }
+
+        rmin(ans, now);
+    } while (next_permutation(all(perm)));
+
+    cout << ans << '\n';
+}
diff --git a/Educational Codeforces Round 41 (Rated for Div. 2)/D. Pair Of Lines.cpp b/Educational Codeforces Round 41 (Rated for Div. 2)/D. Pair Of Lines.cpp
new file mode 100644
index 0000000..d4c8500
--- /dev/null
+++ b/Educational Codeforces Round 41 (Rated for Div. 2)/D. Pair Of Lines.cpp	
@@ -0,0 +1,206 @@
+/* Problem URL: https://codeforces.com/contest/961/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+// Geometria
+
+typedef long long ld;
+const ld DINF = 1e18;
+const ld pi = acos(-1.0);
+const ld eps = 1e-9;
+
+#define sq(x) ((x)*(x))
+
+bool eq(ld a, ld b) {
+	return abs(a - b) <= eps;
+}
+
+struct pt { // ponto
+	ld x, y;
+	pt(ld x_ = 0, ld y_ = 0) : x(x_), y(y_) {}
+	bool operator < (const pt p) const {
+		if (!eq(x, p.x)) return x < p.x;
+		if (!eq(y, p.y)) return y < p.y;
+		return 0;
+	}
+	bool operator == (const pt p) const {
+		return eq(x, p.x) and eq(y, p.y);
+	}
+	pt operator + (const pt p) const { return pt(x+p.x, y+p.y); }
+	pt operator - (const pt p) const { return pt(x-p.x, y-p.y); }
+	pt operator * (const ld c) const { return pt(x*c  , y*c  ); }
+	pt operator / (const ld c) const { return pt(x/c  , y/c  ); }
+	ld operator * (const pt p) const { return x*p.x + y*p.y; }
+	ld operator ^ (const pt p) const { return x*p.y - y*p.x; }
+	friend istream& operator >> (istream& in, pt& p) {
+		return in >> p.x >> p.y;
+	}
+};
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    if (n <= 3) {
+        cout << "YES\n";
+        return 0;
+    }
+
+    V<pt> a(n);
+    cin >> a;
+
+    V<bool> group(n);
+    V<bool> invalid(n);
+
+    auto iscol = [&](pt a, pt b, pt c) {
+        return (b.y - a.y) * (c.x - b.x) == (c.y - b.y) * (b.x - a.x);
+    };
+
+    auto check = [&]() {
+        int first = 0;
+        while (group[first]) {
+            first++;
+        }
+
+        int second = first + 1;
+        while (group[second]) {
+            second++;
+        }
+
+        rep(i, n) {
+            if (group[i]) {
+                continue;
+            }
+
+            if (!iscol(a[first], a[second], a[i])) {
+                return false;
+            }
+        }
+
+        return true;
+    };
+
+    int c = 0;
+
+    rep(i, n) {
+        if (iscol(a[0], a[1], a[i])) {
+            group[i] = true;
+        } else {
+            c++;
+        }
+    }
+
+    if (c <= 2 || check()) {
+        cout << "YES\n";
+        return 0;
+    }
+
+    fill(all(group), false);
+    c = 0;
+    rep(i, n) {
+        if (iscol(a[0], a[2], a[i])) {
+            group[i] = true;
+        } else {
+            c++;
+        }
+    }
+
+    if (c <= 2 || check()) {
+        cout << "YES\n";
+        return 0;
+    }
+
+    fill(all(group), false);
+    c = 0;
+    rep(i, n) {
+        if (iscol(a[1], a[2], a[i])) {
+            group[i] = true;
+        } else {
+            c++;
+        }
+    }
+
+    if (c <= 2 || check()) {
+        cout << "YES\n";
+        return 0;
+    }
+
+    cout << "NO\n";
+}
diff --git a/Educational Codeforces Round 41 (Rated for Div. 2)/E. Tufurama.cpp b/Educational Codeforces Round 41 (Rated for Div. 2)/E. Tufurama.cpp
new file mode 100644
index 0000000..825a670
--- /dev/null
+++ b/Educational Codeforces Round 41 (Rated for Div. 2)/E. Tufurama.cpp	
@@ -0,0 +1,139 @@
+/* Problem URL: https://codeforces.com/contest/961/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    vi fds(n);
+    cin >> fds;
+
+    int size = n;
+    while (__builtin_popcount(size) != 1) {
+        size++;
+        fds.push_back(0);
+    }
+
+    vvl mergeseg(size * 2);
+
+    function<void(int, int, int)> build = [&](int i, int l, int r) {
+        if (l == r) {
+            mergeseg[i] = {fds[i - size]};
+            return;
+        }
+
+        int mid = (l + r) >> 1;
+
+        build(i * 2, l, mid);
+        build(i * 2 + 1, mid + 1, r);
+
+        merge(all(mergeseg[i * 2]), all(mergeseg[i * 2 + 1]), back_inserter(mergeseg[i]));
+    };
+
+    build(1, 0, size - 1);
+
+    function<ll(int, int, int, int, int, ll)> query = [&](int i, int l, int r, int tl, int tr, ll v) -> ll {
+        if (l > tr || r < tl) {
+            return 0LL;
+        }
+
+        if (l >= tl && r <= tr) {
+            auto lower = lower_bound(all(mergeseg[i]), v);
+            return mergeseg[i].end() - lower;
+        }
+
+        int mid = (l + r) >> 1;
+        
+        return query(i * 2, l, mid, tl, tr, v) + query(i * 2 + 1, mid + 1, r, tl, tr, v);
+    };
+
+    ll ans = 0;
+
+    rep(i, n) {
+        rmin(fds[i], n);
+        if (fds[i] <= i + 1) {
+            continue;
+        }
+
+        ans += query(1, 0, size - 1, i + 1, fds[i] - 1, i + 1);
+    }
+    cout << ans << '\n';
+}
diff --git a/Educational Codeforces Round 42 (Rated for Div. 2)/A. Equator.cpp b/Educational Codeforces Round 42 (Rated for Div. 2)/A. Equator.cpp
new file mode 100644
index 0000000..a7ebd8c
--- /dev/null
+++ b/Educational Codeforces Round 42 (Rated for Div. 2)/A. Equator.cpp	
@@ -0,0 +1,98 @@
+/* Problem URL: https://codeforces.com/contest/962/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+    vi a(n);
+    cin >> a;
+
+    ll total = accumulate(all(a), 0LL);
+
+    ll now = 0;
+    int i = 0;
+    while (now < ((total + 1) >> 1)) {
+        now += a[i];
+        i++;
+    }
+
+    cout << i << '\n';
+}
diff --git a/Educational Codeforces Round 42 (Rated for Div. 2)/B. Students in Railway Carriage.cpp b/Educational Codeforces Round 42 (Rated for Div. 2)/B. Students in Railway Carriage.cpp
new file mode 100644
index 0000000..8df68ad
--- /dev/null
+++ b/Educational Codeforces Round 42 (Rated for Div. 2)/B. Students in Railway Carriage.cpp	
@@ -0,0 +1,122 @@
+/* Problem URL: https://codeforces.com/contest/962/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, a, b;
+    cin >> n >> a >> b;
+
+    string fds;
+    cin >> fds;
+
+    vi c = {a, b};
+
+    int s = c[0] > c[1] ? 0 : 1;
+
+    int prev = -1;
+    int ans = 0;
+
+    rep(i, n) {
+        if (fds[i] == '*') {
+            int now = s;
+            for (int j = prev + 1; j < i; j++) {
+                if (c[now]) {
+                    ans++;
+                    c[now]--;
+                }
+                now ^= 1;
+            }
+
+            s = c[0] > c[1] ? 0 : 1;
+            prev = i;
+        }
+    }
+
+    int now = s;
+    for (int j = prev + 1; j < n; j++) {
+        if (c[now]) {
+            ans++;
+            c[now]--;
+        }
+        now ^= 1;
+    }
+
+    cout << ans << '\n';
+}
diff --git a/Educational Codeforces Round 42 (Rated for Div. 2)/C. Make a Square.cpp b/Educational Codeforces Round 42 (Rated for Div. 2)/C. Make a Square.cpp
new file mode 100644
index 0000000..d77774b
--- /dev/null
+++ b/Educational Codeforces Round 42 (Rated for Div. 2)/C. Make a Square.cpp	
@@ -0,0 +1,118 @@
+/* Problem URL: https://codeforces.com/contest/962/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    string n;
+    cin >> n;
+
+    int ans = INT32_MAX >> 1;
+
+    nrep(i, 1, 1e5) {
+        string now = to_string((ll)i * i);
+
+        int j = 0;
+        int k = 0;
+
+        int tmp = 0;
+
+        while (j < n.size() && k < now.size()) {
+            if (n[j] == now[k]) {
+                k++;
+            } else {
+                tmp++;
+            }
+            j++;
+        }
+
+        if (k < now.size()) {
+            continue;
+        }
+
+        rmin(ans, tmp + (int)n.size() - j);
+    }
+
+    if (ans == INT32_MAX >> 1) {
+        cout << "-1\n";
+        return 0;
+    }
+
+    cout << ans << '\n';
+}
diff --git a/Educational Codeforces Round 42 (Rated for Div. 2)/D. Merge Equals.cpp b/Educational Codeforces Round 42 (Rated for Div. 2)/D. Merge Equals.cpp
new file mode 100644
index 0000000..091b4da
--- /dev/null
+++ b/Educational Codeforces Round 42 (Rated for Div. 2)/D. Merge Equals.cpp	
@@ -0,0 +1,116 @@
+/* Problem URL: https://codeforces.com/contest/962/problem/D */
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    vl a(n);
+    cin >> a;
+
+    set<ll> act;
+    map<ll, int> pos;
+
+    rep(i, n) {
+        if (!act.count(a[i])) {
+            act.insert(a[i]);
+            pos[a[i]] = i;
+            continue;
+        }
+
+        act.erase(a[i]);
+        pos.erase(a[i]);
+        a[i] *= 2;
+        i--;
+    }
+
+    V<pair<int, ll>> ans;
+    repv(i, pos) {
+        ans.emplace_back(i.second, i.first);
+    }
+
+    sortv(ans);
+
+    cout << ans.size() << '\n';
+    repv(i, ans) {
+        cout << i.second << ' ';
+    }
+    cout << '\n';
+}
diff --git a/Educational Codeforces Round 42 (Rated for Div. 2)/E. Byteland, Berland and Disputed Cities.cpp b/Educational Codeforces Round 42 (Rated for Div. 2)/E. Byteland, Berland and Disputed Cities.cpp
new file mode 100644
index 0000000..cf36c03
--- /dev/null
+++ b/Educational Codeforces Round 42 (Rated for Div. 2)/E. Byteland, Berland and Disputed Cities.cpp	
@@ -0,0 +1,227 @@
+/* Problem URL: https://codeforces.com/contest/962/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    vl r;
+    vl b;
+    vl p;
+
+    rep(i, n) {
+        ll x;
+        char o;
+        cin >> x >> o;
+
+        if (o == 'R') {
+            r.push_back(x);
+            continue;
+        }
+
+        if (o == 'B') {
+            b.push_back(x);
+            continue;
+        }
+
+        p.push_back(x);
+    }
+
+    sortv(r);
+    sortv(b);
+    sortv(p);
+
+    ll ans = 0;
+    nrep(i, 1, p.size()) {
+        ans += p[i] - p[i - 1];
+    }
+
+    V<pair<ll, int>> tmp;
+
+    repv(i, r) {
+        tmp.emplace_back(i, 0);
+    }
+    repv(i, p) {
+        tmp.emplace_back(i, 1);
+    }
+    sortv(tmp);
+
+    nrep(i, 1, tmp.size()) {
+        if (tmp[i].second == 0 || tmp[i - 1].second == 0) {
+            ans += tmp[i].first - tmp[i - 1].first;
+        }
+    }
+
+    tmp.clear();
+
+    repv(i, b) {
+        tmp.emplace_back(i, 0);
+    }
+    repv(i, p) {
+        tmp.emplace_back(i, 1);
+    }
+    sortv(tmp);
+
+    nrep(i, 1, tmp.size()) {
+        if (tmp[i].second == 0 || tmp[i - 1].second == 0) {
+            ans += tmp[i].first - tmp[i - 1].first;
+        }
+    }
+
+    repv(i, r) {
+        tmp.emplace_back(i, 2);
+    }
+    
+    sortv(tmp);
+
+    int prev = -1;
+    bool ry = false;
+    bool by = false;
+    rep(i, tmp.size()) {
+        if (tmp[i].second == 1) {
+            if (prev == -1 || (!ry && !by)) {
+                prev = i;
+                ry = false;
+                by = false;
+                continue;
+            }
+
+            if (ry && by) {
+                int prevr = -1;
+                int prevb = -1;
+                ll maxr = 0;
+                ll maxb = 0;
+
+                nrep(j, prev + 1, i) {
+                    if (tmp[j].second == 2) {
+                        if (prevr == -1) {
+                            rmax(maxr, tmp[j].first - tmp[prev].first);
+                        } else {
+                            rmax(maxr, tmp[j].first - tmp[prevr].first);
+                        }
+                        prevr = j;
+                        continue;
+                    }
+
+                    if (prevb == -1) {
+                        rmax(maxb, tmp[j].first - tmp[prev].first);
+                    } else {
+                        rmax(maxb, tmp[j].first - tmp[prevb].first);
+                    }
+                    prevb = j;
+                }
+
+                rmax(maxr, tmp[i].first - tmp[prevr].first);
+                rmax(maxb, tmp[i].first - tmp[prevb].first);
+
+                // cout << maxr << ' ' << maxb << ' ' << tmp[i].first - tmp[prev].first << '\n';
+                ans -= max(maxr + maxb, tmp[i].first - tmp[prev].first);
+
+                prev = i;
+                ry = false;
+                by = false;
+                continue;
+            }
+
+            ll maximal = 0;
+            nrep(j, prev + 1, i + 1) {
+                if (i > 0) {
+                    rmax(maximal, tmp[j].first - tmp[j - 1].first);
+                }
+            }
+
+            ans -= maximal;
+            prev = i;
+            ry = false;
+            by = false;
+            continue;
+        }
+
+        if (tmp[i].second == 2) {
+            ry = true;
+            continue;
+        }
+
+        by = true;
+    }
+
+    cout << ans << '\n';
+}
diff --git a/Educational Codeforces Round 43 (Rated for Div. 2)/A. Minimum Binary Number.cpp b/Educational Codeforces Round 43 (Rated for Div. 2)/A. Minimum Binary Number.cpp
new file mode 100644
index 0000000..ab016c9
--- /dev/null
+++ b/Educational Codeforces Round 43 (Rated for Div. 2)/A. Minimum Binary Number.cpp	
@@ -0,0 +1,103 @@
+/* Problem URL: https://codeforces.com/contest/976/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    string a;
+    cin >> a;
+
+    bool one = false;
+    string ans;
+    rep(i, n) {
+        if (a[i] == '1') {
+            one = true;
+            continue;
+        }
+        ans.push_back('0');
+    }
+
+    if (one) {
+        cout << '1';
+    }
+    cout << ans << '\n';
+}
diff --git a/Educational Codeforces Round 43 (Rated for Div. 2)/B. Lara Croft and the New Game.cpp b/Educational Codeforces Round 43 (Rated for Div. 2)/B. Lara Croft and the New Game.cpp
new file mode 100644
index 0000000..702872d
--- /dev/null
+++ b/Educational Codeforces Round 43 (Rated for Div. 2)/B. Lara Croft and the New Game.cpp	
@@ -0,0 +1,105 @@
+/* Problem URL: https://codeforces.com/contest/976/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    ll n, m, k;
+    cin >> n >> m >> k;
+
+    if (k < n) {
+        cout << k + 1 << ' ' << 1 << '\n';
+        return 0;
+    }
+
+    k -= n;
+
+    ll loop = (m - 1) * 2;
+    ll lin =  n - k / (m - 1);
+    ll col = k % loop;
+
+    // cout << lin << ' ' << col << '\n';
+
+    if (col < m - 1) {
+        cout << lin << ' ' << col + 2 << '\n';
+        return 0;
+    }
+
+    cout << lin << ' ' << m - col % (m - 1) << '\n';
+}
diff --git a/Educational Codeforces Round 43 (Rated for Div. 2)/C. Nested Segments.cpp b/Educational Codeforces Round 43 (Rated for Div. 2)/C. Nested Segments.cpp
new file mode 100644
index 0000000..067fa4b
--- /dev/null
+++ b/Educational Codeforces Round 43 (Rated for Div. 2)/C. Nested Segments.cpp	
@@ -0,0 +1,137 @@
+/* Problem URL: https://codeforces.com/contest/976/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    V<tuple<ll, ll, int>> fds(n);
+    rep(i, n) {
+        auto &[l, r, j] = fds[i];
+        cin >> l >> r;
+        j = i;
+    }
+
+    sort(all(fds), [&](tuple<ll, ll, int> &a, tuple<ll, ll, int> &b){
+         auto [li, ri, _] = a;
+         auto [lj, rj, __] = b;
+         if (li == lj) {
+            return ri > rj;
+         }
+         return li < lj;
+         });
+
+    vvi sparse(25, vi(n));
+    rep(i, n) {
+        sparse[0][i] = get<1>(fds[i]);
+    }
+
+    nrep(j, 1, 25) {
+        for (int i = 0; i + (1 << (j - 1)) < n; i++) {
+            sparse[j][i] = min(sparse[j - 1][i], sparse[j - 1][i + (1 << (j - 1))]);
+        }
+    }
+
+    auto query = [&](int l, int r) {
+        int log = 31 - __builtin_clz(r - l + 1);
+        return min(sparse[log][l], sparse[log][r - (1 << log) + 1]);
+    };
+
+    int l = -1;
+    int r = -1;
+
+    rep(i, n - 1) {
+        auto [li, ri, ii] = fds[i];
+        if (query(i + 1, n - 1) <= ri) {
+            nrep(j, i + 1, n) {
+                auto [lj, rj, ij] = fds[j];
+                if (lj >= li && rj <= ri) {
+                    l = ij + 1;
+                    r = ii + 1;
+                    break;
+                }
+            }
+            break;
+        }
+    }
+
+    cout << l << ' ' << r << '\n';
+}
diff --git a/Educational Codeforces Round 43 (Rated for Div. 2)/D. Degree Set.cpp b/Educational Codeforces Round 43 (Rated for Div. 2)/D. Degree Set.cpp
new file mode 100644
index 0000000..199e0f6
--- /dev/null
+++ b/Educational Codeforces Round 43 (Rated for Div. 2)/D. Degree Set.cpp	
@@ -0,0 +1,123 @@
+/* Problem URL: https://codeforces.com/contest/976/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int size;
+    cin >> size;
+
+    vi fds(size);
+    cin >> fds;
+
+    int n = fds.back() + 1;
+
+    vi ans(n, fds.back());
+    rep(i, fds.size()) {
+        ans[i] = fds[fds.size() - i - 1];
+    }
+    nrep(i, fds.size(), n) {
+        ans[i] = fds[0];
+    }
+
+    V<pair<int, int>> edges;
+    int valid = n - 1;
+
+    rep(i, n) {
+        if (ans[i] == 0) {
+            break;
+        }
+
+        int now = valid;
+        while (ans[i] != 0) {
+            ans[i]--;
+            ans[now]--;
+            edges.emplace_back(i + 1, now + 1);
+            if (ans[now] == 0) {
+                valid = now - 1;
+            }
+            now--;
+        }
+    }
+
+    cout << edges.size() << '\n';
+    repv(i, edges) {
+        cout << i.first << ' ' << i.second << '\n';
+    }
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/A. Disjoint Sets Union.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/A. Disjoint Sets Union.cpp
new file mode 100644
index 0000000..c7c8021
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/A. Disjoint Sets Union.cpp	
@@ -0,0 +1,116 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/1/practice/contest/289390/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    vi dsu(n);
+    rep(i, n) {
+        dsu[i] = i;
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        dsu[find_p(b)] = find_p(a);
+    };
+
+    while (m--) {
+        string op;
+        cin >> op;
+        int a, b;
+        cin >> a >> b;
+        a--, b--;
+
+        if (op[0] == 'u') {
+            join(a, b);
+            continue;
+        }
+
+        cout << (find_p(a) == find_p(b) ? "YES\n" : "NO\n");
+    }
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/B. Disjoint Sets Union 2.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/B. Disjoint Sets Union 2.cpp
new file mode 100644
index 0000000..dff4d73
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/B. Disjoint Sets Union 2.cpp	
@@ -0,0 +1,137 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/1/practice/contest/289390/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    vi dsu(n);
+    vi sizes(n, 1);
+    vi maximal(n);
+    vi minimal(n);
+    rep(i, n) {
+        dsu[i] = i;
+        maximal[i] = i + 1;
+        minimal[i] = i + 1;
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        a = find_p(a);
+        b = find_p(b);
+
+        if (a == b) {
+            return;
+        }
+
+        rmax(maximal[a], maximal[b]);
+        rmin(minimal[a], minimal[b]);
+        sizes[a] += sizes[b];
+        dsu[b] = a;
+    };
+
+    while (m--) {
+        string op;
+        cin >> op;
+
+        int a;
+        cin >> a;
+        a--;
+
+        if (op[0] == 'u') {
+            int b;
+            cin >> b;
+            b--;
+            join(a, b);
+            continue;
+        }
+
+        a = find_p(a);
+
+        cout << minimal[a] << ' ' << maximal[a] << ' ' << sizes[a] << '\n';
+    }
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/D. Cutting a graph.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/D. Cutting a graph.cpp
new file mode 100644
index 0000000..86362cd
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/D. Cutting a graph.cpp	
@@ -0,0 +1,135 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/1/practice/contest/289390/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m, k;
+    cin >> n >> m >> k;
+
+    while (m--) {
+        int a, b;
+        cin >> a >> b;
+    }
+
+    vi dsu(n);
+    rep(i, n) {
+        dsu[i] = i;
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        dsu[find_p(b)] = find_p(a);
+    };
+
+    V<tuple<int, int, int>> query(k);
+    V<string> ans;
+
+    while (k--) {
+        string a;
+        int b, c;
+        cin >> a >> b >> c;
+
+        if (a[0] == 'a') {
+            query[k] = {0, b - 1, c - 1};
+            continue;
+        }
+
+        query[k] = {1, b - 1, c - 1};
+    }
+
+    for (auto [op, a, b] : query) {
+        if (op == 0) {
+            ans.emplace_back((find_p(a) == find_p(b) ? "YES\n" : "NO\n"));
+            continue;
+        }
+
+        join(a, b);
+    }
+
+    for (int i = ans.size() - 1; i >= 0; i--) {
+        cout << ans[i];
+    }
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/E. Monkeys.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/E. Monkeys.cpp
new file mode 100644
index 0000000..13ae38c
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 1/E. Monkeys.cpp	
@@ -0,0 +1,180 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/1/practice/contest/289390/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    V<array<int, 2>> graph(n);
+
+    rep(i, n) {
+        int a, b;
+        cin >> a >> b;
+
+        graph[i] = {a - 1, b - 1};
+    }
+
+    V<tuple<int, int, int>> edges(m);
+
+    while (m--) {
+        int i, p;
+        cin >> i >> p;
+        i--, p--;
+
+        edges[m] = {i, p, graph[i][p]};
+        graph[i][p] = -1;
+    }
+
+    vi dsu(n);
+    V<set<int>> nodes(n);
+    rep(i, n) {
+        dsu[i] = i;
+        nodes[i].insert(i);
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        a = find_p(a);
+        b = find_p(b);
+
+        if (a == b) {
+            return;
+        }
+
+        if (a > b) {
+            swap(a, b);
+        }
+
+        if (nodes[a].size() < nodes[b].size()) {
+            swap(nodes[a], nodes[b]);
+        }
+
+        repv(i, nodes[b]) {
+            nodes[a].insert(i);
+        }
+        nodes[b].clear();
+
+        dsu[b] = a;
+    };
+
+    rep(i, n) {
+        if(graph[i][0] >= 0) {
+            join(i, graph[i][0]);
+        }
+
+        if (graph[i][1] >= 0) {
+            join(i, graph[i][1]);
+        }
+    }
+
+    vi ans(n, -1);
+
+    rep(k, edges.size()) {
+        auto [i, p, j] = edges[k];
+
+        i = find_p(i);
+        j = find_p(j);
+
+        if (i != j) {
+            if (i > j) {
+                swap(i, j);
+            }
+
+            if (i == 0) {
+                repv(l, nodes[j]) {
+                    ans[l] = edges.size() - k - 1;
+                }
+            }
+
+            join(i, j);
+        }
+    }
+
+    repv(i, ans) {
+        cout << i << '\n';
+    }
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/A. People are leaving.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/A. People are leaving.cpp
new file mode 100644
index 0000000..b215336
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/A. People are leaving.cpp	
@@ -0,0 +1,128 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/A */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    vi dsu(n + 1);
+    rep(i, n + 1) {
+        dsu[i] = i;
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        a = find_p(a);
+        b = find_p(b);
+
+        if (a < b) {
+            swap(a, b);
+        }
+
+        dsu[b] = a;
+    };
+
+    while (m--) {
+        char op;
+        int x;
+        cin >> op >> x;
+        x--;
+
+        if (op == '-') {
+            join(x, x + 1);
+            continue;
+        }
+
+        x = find_p(x);
+        if (x == n) {
+            cout << "-1\n";
+            continue;
+        }
+
+        cout << x + 1 << '\n';
+    }
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/B. Parking.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/B. Parking.cpp
new file mode 100644
index 0000000..662837b
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/B. Parking.cpp	
@@ -0,0 +1,115 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/B */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    vi dsu(n);
+    rep(i, n) {
+        dsu[i] = i;
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        dsu[find_p(a)] = find_p(b);
+    };
+
+    vi ans(n);
+
+    rep(i, n) {
+        int x;
+        cin >> x;
+        x--;
+
+        x = find_p(x);
+        ans[i] = x + 1;
+        join(x, (x + 1) * ((x + 1) < n));
+    }
+
+    cout << ans;
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/C. Restructuring Company.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/C. Restructuring Company.cpp
new file mode 100644
index 0000000..60c41c5
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/C. Restructuring Company.cpp	
@@ -0,0 +1,145 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, q;
+    cin >> n >> q;
+
+    vi dsui(n);
+    vi dsup(n);
+    rep(i, n) {
+        dsui[i] = i;
+        dsup[i] = i;
+    }
+
+    function<int(vi&, int)> find_p = [&](vi &dsu, int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu, dsu[i]);
+    };
+
+    auto join = [&](vi &dsu, int a, int b) {
+        a = find_p(dsu, a);
+        b = find_p(dsu, b);
+        if (a < b) {
+            swap(a, b);
+        }
+
+        dsu[b] = a;
+    };
+
+    while (q--) {
+        int op;
+        cin >> op;
+
+        if (op == 1) {
+            int a, b;
+            cin >> a >> b;
+            a--, b--;
+
+            join(dsui, a, b);
+            continue;
+        }
+
+        if (op == 2) {
+            int x, y;
+            cin >> x >> y;
+            x--, y--;
+
+            while (x = find_p(dsup, x), x < y) {
+                join(dsup, x, x + 1);
+                join(dsui, x, x + 1);
+            }
+            continue;
+        }
+
+        int a, b;
+        cin >> a >> b;
+        a--, b--;
+
+        if (find_p(dsui, a) == find_p(dsui, b) || find_p(dsup, a) == find_p(dsup, b)) {
+            cout << "YES\n";
+        } else {
+            cout << "NO\n";
+        }
+    }
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/D. Bosses.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/D. Bosses.cpp
new file mode 100644
index 0000000..21bff9f
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/D. Bosses.cpp	
@@ -0,0 +1,131 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    vi dsu(n);
+    vi ans(n);
+
+    rep(i, n) {
+        dsu[i] = i;
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+
+        if (dsu[dsu[i]] != dsu[i]) {
+            int prev = dsu[i];
+            int tmp = find_p(dsu[i]);
+            ans[i] += ans[prev] + 1;
+            dsu[i] = tmp;
+        }
+
+        return dsu[i];
+    };
+
+    auto join = [&](int a, int b) {
+        dsu[find_p(a)] = find_p(b);
+    };
+
+    while (m--) {
+        int op;
+        cin >> op;
+
+        if (op == 1) {
+            int a, b;
+            cin >> a >> b;
+            a--, b--;
+            join(a, b);
+            continue;
+        }
+
+        int a;
+        cin >> a;
+        a--;
+
+        int p = find_p(a);
+        cout << (p == a ? 0 : ans[a] + 1) << '\n';
+    }
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/E. Spanning Tree.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/E. Spanning Tree.cpp
new file mode 100644
index 0000000..6465d36
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/E. Spanning Tree.cpp	
@@ -0,0 +1,122 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    V<tuple<int, int, int>> edges(m);
+    for (auto &[c, u, v] : edges) {
+        cin >> u >> v >> c;
+        u--, v--;
+    }
+
+    sortv(edges);
+
+    vi dsu(n);
+    rep(i, n) {
+        dsu[i] = i;
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        a = find_p(a);
+        b = find_p(b);
+
+        dsu[b] = a;
+        return a != b;
+    };
+
+    ll ans = 0;
+    for (auto [c, u, v] : edges) {
+        if (join(u, v)) {
+            ans += c;
+        }
+    }
+
+    cout << ans << '\n';
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/F. Dense spanning tree.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/F. Dense spanning tree.cpp
new file mode 100644
index 0000000..1a1a96d
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/F. Dense spanning tree.cpp	
@@ -0,0 +1,156 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/F */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    vvi graph(n);
+
+    V<tuple<ll, int, int>> edges(m);
+    for (auto &[c, u, v] : edges) {
+        cin >> u >> v >> c;
+        u--, v--;
+    }
+
+    vi dsu(n);
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        a = find_p(a);
+        b = find_p(b);
+
+        dsu[b] = a;
+
+        return a != b;
+    };
+
+    sortv(edges);
+    ll oo = INT64_MAX >> 1;
+
+    auto getans = [&]() {
+        ll ans = oo;
+
+        rep(i, m) {
+            rep(j, n) {
+                dsu[j] = j;
+            }
+
+            ll minimal = oo;
+            ll maximal = -oo;
+
+            int num = n - 1;
+
+            int j = i;
+            while (j < m && num > 0) {
+                auto [c, u, v] = edges[j];
+                if (join(u, v)) {
+                    rmin(minimal, c);
+                    rmax(maximal, c);
+                    num--;
+                }
+                j++;
+            }
+
+            if (num > 0) {
+                return ans;
+            }
+
+            rmin(ans, abs(maximal - minimal));
+        }
+
+        return ans;
+    };
+
+    ll ans = getans();
+    if (ans == oo) {
+        cout << "NO\n";
+        return 0;
+    }
+
+    cout << "YES\n" << ans << '\n';
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/G. No refuel.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/G. No refuel.cpp
new file mode 100644
index 0000000..5182f30
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/G. No refuel.cpp	
@@ -0,0 +1,123 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/G */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, k;
+    cin >> n >> k;
+
+    V<tuple<int, int, int>> edges(k);
+
+    for (auto &[c, u, v] : edges) {
+        cin >> u >> v >> c;
+        u--, v--;
+    }
+
+    vi dsu(n);
+    rep(i, n) {
+        dsu[i] = i;
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        a = find_p(a);
+        b = find_p(b);
+
+        dsu[b] = a;
+
+        return a != b;
+    };
+
+    sortv(edges);
+    int ans = 0;
+    for (auto [c, u, v] : edges) {
+        if (join(u, v)) {
+            ans = c;
+        }
+    }
+
+    cout << ans << '\n';
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/H. Oil business.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/H. Oil business.cpp
new file mode 100644
index 0000000..3688eaf
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/H. Oil business.cpp	
@@ -0,0 +1,146 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/H */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    ll s;
+    cin >> n >> m >> s;
+
+    vi dsu(n);
+    rep(i, n) {
+        dsu[i] = i;
+    }
+
+    function<int(int)> find_p = [&](int i) {
+        if (dsu[i] == i) {
+            return i;
+        }
+        return dsu[i] = find_p(dsu[i]);
+    };
+
+    auto join = [&](int a, int b) {
+        a = find_p(a);
+        b = find_p(b);
+
+        dsu[b] = a;
+
+        return a != b;
+    };
+
+    V<tuple<ll, int, int, int>> edges(m);
+    rep(i, m) {
+        auto &[c, j, u, v] = edges[i];
+        cin >> u >> v >> c;
+        u--, v--;
+        j = i;
+    }
+
+    sort(all(edges), greater<>());
+
+    V<pair<ll, int>> potential;
+    for (auto [c, i, u, v] : edges) {
+        if (!join(u, v)) {
+            potential.emplace_back(c, i);
+        }
+    }
+
+    rep(i, n) {
+        dsu[i] = i;
+    }
+    reverse(all(potential));
+
+    vi ans;
+    ll total = 0;
+
+    for (auto [c, i] : potential) {
+        if (total + c > s) {
+            break;
+        }
+        
+        ans.push_back(i + 1);
+        total += c;
+    }
+
+    cout << ans.size() << '\n';
+    rep(i, ans.size()) {
+        cout << ans[i] << " \n"[i == ans.size() - 1];
+    }
+}
diff --git a/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/I. Bipartite Graph.cpp b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/I. Bipartite Graph.cpp
new file mode 100644
index 0000000..d318ee1
--- /dev/null
+++ b/ITMO Academy: pilot course - Disjoint Sets Union - Step 2/I. Bipartite Graph.cpp	
@@ -0,0 +1,142 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/7/2/practice/contest/289391/problem/I */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    vi dsu(n);
+    rep(i, n) {
+        dsu[i] = i;
+    }
+
+    vi depth(n);
+
+    function<pair<int, int>(int)> find_p = [&](int i) -> pair<int, int>{
+        if (dsu[i] == i) {
+            return {i, 0};
+        }
+
+        auto ans = find_p(dsu[i]);
+        dsu[i] = ans.first;
+        depth[i] ^= ans.second;
+
+        return {dsu[i], depth[i]};
+    };
+
+    auto join = [&](int a, int b) {
+        auto ap = find_p(a);
+        auto bp = find_p(b);
+
+        dsu[bp.first] = ap.first;
+        depth[bp.first] = (1 ^ bp.second ^ ap.second);
+    };
+    
+    int shift = 0;
+    function<void(int, int)> func[] = {
+        [&](int a, int b) {
+            join(a, b);
+        },
+        [&](int a, int b) {
+            find_p(a);
+            find_p(b);
+
+            int ca = depth[a];
+            int cb = depth[b];
+
+            if (ca == cb) {
+                cout << "YES\n";
+                shift++;
+                return;
+            }
+
+            cout << "NO\n";
+        }
+    };
+
+    while (m--) {
+        int op, a, b;
+        cin >> op >> a >> b;
+        a = (a + shift) % n;
+        b = (b + shift) % n;
+        func[op](a, b);
+    }
+}
diff --git a/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/B. Add Arithmetic Progression On Segment.cpp b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/B. Add Arithmetic Progression On Segment.cpp
index e2c2dab..5d4d555 100644
--- a/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/B. Add Arithmetic Progression On Segment.cpp	
+++ b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/B. Add Arithmetic Progression On Segment.cpp	
@@ -80,5 +80,102 @@ int main()
     ios::sync_with_stdio(false);
     cin.tie(nullptr);
 
+    int n, m;
+    cin >> n >> m;
 
+    if (n > 1) {
+        n = 1 << (32 - __builtin_clz(n - 1));
+    }
+
+    vl seg(n * 2);
+    vl lazyconst(n * 2);
+    vl lazyprog(n * 2);
+
+    auto propagateconst = [&](int i) {
+        if (lazyconst[i] == 0) {
+            return;
+        }
+
+        if (i >= n) {
+            seg[i] += lazyconst[i];
+            lazyconst[i] = 0;
+            return;
+        }
+
+        lazyconst[i * 2]  += lazyconst[i];
+        lazyconst[i * 2 + 1] += lazyconst[i];
+        lazyconst[i] = 0;
+    };
+
+    auto propagateprog = [&](int i) {
+        if (lazyprog[i] == 0) {
+            return;
+        }
+
+        if (i >= n) {
+            seg[i] += lazyprog[i] * (i - n + 1);
+            lazyprog[i] = 0;
+            return;
+        }
+
+        lazyprog[i * 2] += lazyprog[i];
+        lazyprog[i * 2 + 1] += lazyprog[i];
+        lazyprog[i] = 0;
+    };
+
+    auto propagate = [&](int i) {
+        propagateconst(i);
+        propagateprog(i);
+    };
+
+    function<void(int, int, int, int, int, ll, ll)> update = [&](int i, int l, int r, int tl, int tr, ll c, ll p) {
+        propagate(i);
+        if (l > tr || r < tl) {
+            return;
+        }
+
+        if (l >= tl && r <= tr) {
+            lazyconst[i] += c;
+            lazyprog[i] += p;
+            propagate(i);
+            return;
+        }
+
+        int mid = (l + r) >> 1;
+
+        update(i * 2, l, mid, tl, tr, c, p);
+        update(i * 2 + 1, mid + 1, r, tl, tr, c, p);
+    };
+
+    function<ll(int, int, int, int)> query = [&](int i, int l, int r, int t) {
+        propagate(i);
+
+        if (i >= n) {
+            return seg[i];
+        }
+
+        int mid = (l + r) >> 1;
+
+        if (mid >= t) {
+            return query(i * 2, l, mid, t);
+        }
+
+        return query(i * 2 + 1, mid + 1, r, t);
+    };
+
+    while (m--) {
+        int op;
+        cin >> op;
+
+        if (op == 1) {
+            ll l, r, a, d;
+            cin >> l >> r >> a >> d;
+            update(1, 0, n - 1, l - 1, r - 1, a - d * l, d);
+            continue;
+        }
+
+        int i;
+        cin >> i;
+        cout << query(1, 0, n - 1, i - 1) << '\n';
+    }
 }
diff --git a/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/C. Painter.cpp b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/C. Painter.cpp
new file mode 100644
index 0000000..5bece8e
--- /dev/null
+++ b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/C. Painter.cpp	
@@ -0,0 +1,189 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/5/4/practice/contest/280801/problem/C */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n;
+    cin >> n;
+
+    int middle = 500000;
+
+    int size = 1 << (32 - __builtin_clz(1e6 + middle + 1));
+
+    struct node {
+        int sum;
+        int seg;
+        bool suf;
+        bool pref;
+        bool total;
+
+        node() = default;
+    };
+
+    V<node> seg(size * 2);
+    V<bool> upd(size * 2);
+    vi lazy(size * 2);
+
+    auto merge = [&](node &a, node &b) -> node {
+        node ans;
+        ans.sum = a.sum + b.sum;
+
+        if (a.total && b.total) {
+            ans.total = true;
+            ans.pref = true;
+            ans.suf = true;
+            ans.seg = 1;
+
+            return ans;
+        }
+
+        ans.seg = a.seg + b.seg - (a.suf && b.pref);
+        ans.pref = a.pref;
+        ans.suf = b.suf;
+        ans.total = false;
+
+        return ans;
+    };
+
+    auto propagate = [&](int i, int l, int r) {
+        if (!upd[i]) {
+            return;
+        }
+
+        upd[i] = false;
+
+        seg[i].sum = lazy[i] * (r - l + 1);
+        seg[i].pref = lazy[i];
+        seg[i].suf = lazy[i];
+        seg[i].total = lazy[i];
+        seg[i].seg = lazy[i];
+
+        if (i < size) {
+            lazy[i * 2] = lazy[i];
+            lazy[i * 2 + 1] = lazy[i];
+            upd[i * 2] = true;
+            upd[i * 2 + 1] = true;
+        }
+
+        return;
+    };
+
+    function<void(int, int, int, int, int, int)> update = [&](int i, int l, int r, int tl, int tr, int v) {
+        propagate(i, l, r);
+        
+        if (l > tr || r < tl) {
+            return;
+        }
+
+        if (l >= tl && r <= tr) {
+            lazy[i] = v;
+            upd[i] = true;
+            propagate(i, l, r);
+            return;
+        }
+
+        int mid = (l + r) >> 1;
+
+        update(i * 2, l, mid, tl, tr, v);
+        update(i * 2 + 1, mid + 1, r, tl, tr, v);
+        
+        seg[i] = merge(seg[i * 2], seg[i * 2 + 1]);
+    };
+
+    auto query = [&]() {
+        propagate(1, 0, size - 1);
+
+        return seg[1];
+    };
+
+    rep(i, n) {
+        char op;
+        int x, l;
+        cin >> op >> x >> l;
+        x += middle;
+
+        op = op == 'B';
+
+        update(1, 0, size - 1, x, x + l - 1, op);
+
+        auto ans = query();
+        cout << ans.seg << ' ' << ans.sum << '\n';
+    }
+}
diff --git a/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/D. Problem About Weighted Sum.cpp b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/D. Problem About Weighted Sum.cpp
new file mode 100644
index 0000000..8e55b0d
--- /dev/null
+++ b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/D. Problem About Weighted Sum.cpp	
@@ -0,0 +1,182 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/5/4/practice/contest/280801/problem/D */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, m;
+    cin >> n >> m;
+
+    vi a(n);
+    cin >> a;
+
+    while (__builtin_popcount(n) != 1) {
+        n++;
+        a.push_back(0);
+    }
+
+    V<pair<ll, ll>> seg(n * 2);
+    vl lazy(n * 2);
+
+    auto merge = [&](pair<ll, ll> a, pair<ll, ll> b) -> pair<ll, ll> {
+        return {a.first + b.first, a.second + b.second};
+    };
+
+    nrep(i, n, n * 2) {
+        seg[i] = {a[i - n], a[i - n] * (i - n + 1)};
+    }
+
+    for (int i = n - 1; i > 0; i--) {
+        seg[i] = merge(seg[i * 2], seg[i * 2 + 1]);
+    }
+
+    auto propagate = [&](int i, int l, int r) {
+        if (lazy[i] == 0) {
+            return;
+        }
+
+        ll size = (r - l + 1);
+
+        seg[i].first += lazy[i] * size;
+        seg[i].second += lazy[i] * (size * (r + l + 2) / 2);
+
+        if (i < n) {
+            lazy[i * 2] += lazy[i];
+            lazy[i * 2 + 1] += lazy[i];
+        }
+
+        lazy[i] = 0;
+    };
+
+    function<void(int, int, int, int, int, int)> update = [&](int i, int l, int r, int tl, int tr, int v) {
+        propagate(i, l, r);
+
+        if (l > tr || r < tl) {
+            return;
+        }
+
+        if (l >= tl && r <= tr) {
+            lazy[i] += v;
+            propagate(i, l, r);
+            return;
+        }
+
+        int mid = (l + r) >> 1;
+
+        update(i * 2, l, mid, tl, tr, v);
+        update(i * 2 + 1, mid + 1, r, tl, tr, v);
+
+        seg[i] = merge(seg[i * 2], seg[i * 2 + 1]);
+    };
+
+    function<pair<ll, ll>(int, int, int, int, int)> query = [&](int i, int l, int r, int tl, int tr) -> pair<ll, ll> {
+        if (l > tr || r < tl) {
+            return {0, 0};
+        }
+
+        propagate(i, l, r);
+
+        if (l >= tl && r <= tr) {
+            return seg[i];
+        }
+
+        int mid = (l + r) >> 1;
+
+        return merge(query(i * 2, l, mid, tl, tr), query(i * 2 + 1, mid + 1, r, tl, tr));
+    };
+
+    while (m--) {
+        int op;
+        cin >> op;
+
+        if (op == 1) {
+            int l, r, d;
+            cin >> l >> r >> d;
+            update(1, 0, n - 1, l - 1, r - 1, d);
+            continue;
+        }
+
+        int l, r;
+        cin >> l >> r;
+
+        auto ans = query(1, 0, n - 1, l - 1, r - 1);
+
+        cout << ans.second - ans.first * (l - 1) << '\n';
+    }
+}
diff --git a/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/E. Wall.cpp b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/E. Wall.cpp
new file mode 100644
index 0000000..200b939
--- /dev/null
+++ b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/E. Wall.cpp	
@@ -0,0 +1,181 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/5/4/practice/contest/280801/problem/E */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, k;
+    cin >> n >> k;
+
+    int prev = n;
+
+    if (n > 1) {
+        n = 1 << (32 - __builtin_clz(n - 1));
+    }
+
+    vl seg(n * 2);
+    V<pair<ll, ll>> lazy(n * 2, {0, 1e5});
+    V<bool> upd(n * 2);
+
+    auto propagate = [&](int i) {
+        if (!upd[i]) {
+            return;
+        }
+
+        upd[i] = false;
+
+        rmax(seg[i], lazy[i].first);
+        rmin(seg[i], lazy[i].second);
+
+        if (i < n) {
+            rmax(lazy[i * 2].first, lazy[i].first);
+            rmin(lazy[i * 2].second, lazy[i].second);
+            if (lazy[i * 2].first > lazy[i * 2].second) {
+                if (lazy[i * 2].first == lazy[i].first) {
+                    lazy[i * 2].second = lazy[i * 2].first;
+                } else {
+                    lazy[i * 2].first = lazy[i * 2].second;
+                }
+            }
+            upd[i * 2] = true;
+            rmax(lazy[i * 2 + 1].first, lazy[i].first);
+            rmin(lazy[i * 2 + 1].second, lazy[i].second);
+            if (lazy[i * 2 + 1].first > lazy[i * 2 + 1].second) {
+                if (lazy[i * 2 + 1].first == lazy[i].first) {
+                    lazy[i * 2 + 1].second = lazy[i * 2 + 1].first;
+                } else {
+                    lazy[i * 2 + 1].first = lazy[i * 2 + 1].first;
+                }
+            }
+            upd[i * 2 + 1] = true;
+        }
+
+        lazy[i] = {0, 1e5};
+    };
+
+    function<void(int, int, int, int, int, int, ll)> update = [&](int i, int l, int r, int tl, int tr, int t, ll v) {
+        propagate(i);
+
+        if (l > tr || r < tl) {
+            return;
+        }
+
+        if (l >= tl && r <= tr) {
+            if (t) {
+                lazy[i].second = v;
+            } else {
+                lazy[i].first = v;
+            }
+            upd[i] = true;
+            propagate(i);
+            return;
+        }
+
+        int mid = (l + r) >> 1;
+
+        update(i * 2, l, mid, tl, tr, t, v);
+        update(i * 2 + 1, mid + 1, r, tl, tr, t, v);
+    };
+
+    function<ll(int, int, int, int)> query = [&](int i, int l, int r, int t) {
+        propagate(i);
+
+        if (i >= n) {
+            return seg[i];
+        }
+
+        int mid = (l + r) >> 1;
+
+        if (mid >= t) {
+            return query(i * 2, l, mid, t);
+        }
+        return query(i * 2 + 1, mid + 1, r, t);
+    };
+
+    while (k--) {
+        int op, l, r, h;
+        cin >> op >> l >> r >> h;
+
+        update(1, 0, n - 1, l, r, op - 1, h);
+    }
+
+    rep(i, prev) {
+        cout << query(1, 0, n - 1, i) << '\n';
+    }
+}
diff --git a/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/F. Mountain.cpp b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/F. Mountain.cpp
new file mode 100644
index 0000000..ec88cc7
--- /dev/null
+++ b/ITMO Academy: pilot course - Segment Tree, part 2 - Step 4/F. Mountain.cpp	
@@ -0,0 +1,426 @@
+/* Problem URL: https://codeforces.com/edu/course/2/lesson/5/4/practice/contest/280801/problem/F */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+class segtree_arithmethic {
+    struct node {
+        int val;
+        int left;
+        int right;
+    };
+
+    struct lazynode {
+        int c;
+        int x;
+        int xi;
+        bool cupd;
+        bool xupd;
+    };
+
+    V<node> seg;
+    V<lazynode> lazy;
+    int n;
+
+    int newnode() {
+        lazy.emplace_back(0LL, 0LL, 0LL, false, false);
+        seg.emplace_back(0LL, -1, -1);
+
+        return seg.size() - 1;
+    }
+
+    void createchildren(int i) {
+        if (seg[i].left == -1) {
+            seg[i].left = newnode();
+        }
+
+        if (seg[i].right == -1) {
+            seg[i].right = newnode();
+        }
+    }
+
+    void propagatear(int i, int l, int r) {
+        if (!lazy[i].xupd) {
+            return;
+        }
+
+        seg[i].val = lazy[i].xi + lazy[i].x * (r - l);
+
+        if (l != r) {
+            createchildren(i);
+
+            int left = seg[i].left;
+            int right = seg[i].right;
+
+            int mid = (l + r) >> 1;
+
+            lazy[left].x = lazy[i].x;
+            lazy[left].c = 0;
+            lazy[left].xi = lazy[i].xi;
+            lazy[left].cupd = false;
+            lazy[left].xupd = true;
+
+            lazy[right].x = lazy[i].x;
+            lazy[right].c = 0;
+            lazy[right].xi = lazy[i].xi + lazy[i].x * (mid - l + 1);
+            lazy[right].cupd = false;
+            lazy[right].xupd = true;
+        }
+
+        lazy[i].xupd = false;
+    };
+
+    void propagatec(int i, int l, int r) {
+        if (!lazy[i].cupd) {
+            return;
+        }
+
+        seg[i].val += lazy[i].c;
+
+        if (l != r) {
+            createchildren(i);
+
+            int left = seg[i].left;
+            int right = seg[i].right;
+
+            lazy[left].c += lazy[i].c;
+            lazy[left].cupd = true;
+
+            lazy[right].c += lazy[i].c;
+            lazy[right].cupd = true;
+        }
+
+        lazy[i].cupd = false;
+        lazy[i].c = 0;
+    }
+
+    void propagate(int i, int l, int r) {
+        propagatear(i, l, r);
+        propagatec(i, l, r);
+    }
+
+    int x;
+    int tl, tr;
+
+    void updatearithmethic(int i, int l, int r, int xi) {
+        propagate(i, l, r);
+
+        if (l > tr || r < tl) {
+            return;
+        }
+
+        if (l >= tl && r <= tr) {
+            lazy[i].x = x;
+            lazy[i].xi = xi;
+            lazy[i].xupd = true;
+            lazy[i].c = 0;
+            lazy[i].cupd = false;
+            propagate(i, l, r);
+            return;
+        }
+
+        int mid = (l + r) >> 1;
+
+        createchildren(i);
+
+        updatearithmethic(seg[i].left, l, mid, xi);
+        updatearithmethic(seg[i].right, mid + 1, r, xi + x * (mid - l + 1));
+
+        seg[i].val = max(seg[seg[i].left].val, seg[seg[i].right].val);
+    }
+
+    int c;
+
+    void updateconst(int i, int l, int r) {
+        propagate(i, l, r);
+
+        if (l > tr || r < tl) {
+            return;
+        }
+
+        if (l >= tl && r <= tr) {
+            lazy[i].c += c;
+            lazy[i].cupd = true;
+            propagate(i, l, r);
+            return;
+        }
+
+        int mid = (l + r) >> 1;
+
+        createchildren(i);
+
+        updateconst(seg[i].left, l, mid);
+        updateconst(seg[i].right, mid + 1, r);
+
+        seg[i].val = max(seg[seg[i].left].val, seg[seg[i].right].val);
+    }
+
+    int h;
+
+    ll query(int i, int l, int r) {
+        propagate(i, l, r);
+
+        if (l == r) {
+            return seg[i].val > h ? -1 : l;
+        }
+        
+        int mid = (l + r) >> 1;
+
+        createchildren(i);
+        propagate(seg[i].left, l, mid);
+        propagate(seg[i].right, mid + 1, r);
+        
+        if (seg[seg[i].left].val > h) {
+            return query(seg[i].left, l, mid);
+        }
+        int res = query(seg[i].right, mid + 1, r);
+        return res == -1 ? mid : res;
+    }
+
+    public:
+    segtree_arithmethic(int n): n(n) {
+        seg.emplace_back(0LL, -1, -1);
+        lazy.emplace_back();
+    }
+
+    void updatearithmethic(int l, int r, ll x) {
+        this->x = x;
+        tl = l;
+        tr = r;
+        updatearithmethic(0, 0, n - 1, x * (-l + 1));
+    }
+
+    void updateconst(int l, int r, ll c) {
+        this->c = c;
+        tl = l;
+        tr = r;
+        updateconst(0, 0, n - 1);
+    }
+
+    ll query(int h) {
+        this->h = h;
+        return query(0, 0, n - 1);
+    }
+};
+
+class segtree_sum {
+    struct node {
+        int val;
+        int left;
+        int right;
+    };
+
+    struct lazynode {
+        int val;
+        bool upd;
+    };
+
+    V<node> seg;
+    V<lazynode> lazy;
+    int n;
+
+    int newnode() {
+        seg.emplace_back(0LL, -1, -1);
+        lazy.emplace_back(0LL, false);
+
+        return seg.size() - 1;
+    }
+
+    void createchildren(int i) {
+        if (seg[i].left == -1) {
+            seg[i].left = newnode();
+        }
+
+        if (seg[i].right == -1) {
+            seg[i].right = newnode();
+        }
+    }
+
+    void propagate(int i, int l, int r) {
+        if (!lazy[i].upd) {
+            return;
+        }
+
+        seg[i].val = lazy[i].val * (r - l + 1);
+
+        if (l != r) {
+            createchildren(i);
+            lazy[seg[i].left] = lazy[i];
+            lazy[seg[i].right] = lazy[i];
+        }
+
+        lazy[i].upd = false;
+    }
+
+    int tl, tr;
+    int v;
+
+    void upd(int i, int l, int r) {
+        propagate(i, l, r);
+
+        if (l > tr || r < tl) {
+            return;
+        }
+
+        if (l >= tl && r <= tr) {
+            lazy[i] = {v, true};
+            propagate(i, l, r);
+            return;
+        }
+
+        int mid = (l + r) >> 1;
+
+        createchildren(i);
+
+        upd(seg[i].left, l, mid);
+        upd(seg[i].right, mid + 1, r);
+
+        seg[i].val = seg[seg[i].left].val + seg[seg[i].right].val;
+    }
+
+    ll query(int i, int l, int r) {
+        if (l > tr || r < tl || i == -1) {
+            return 0LL;
+        }
+
+        propagate(i, l, r);
+
+        if (l >= tl && r <= tr) {
+            return seg[i].val;
+        }
+
+        int mid = (l + r) >> 1;
+
+        return query(seg[i].left, l, mid) + query(seg[i].right, mid + 1, r);
+    }
+
+    public:
+    segtree_sum(int n): n(n) {
+        seg.emplace_back(0LL, -1, -1);
+        lazy.emplace_back(0LL, false);
+    }
+
+    void update(int l, int r, int d) {
+        tl = l;
+        tr = r;
+        v = d;
+        upd(0, 0, n - 1);
+    }
+
+    ll query(int l, int r) {
+        tl = l;
+        tr = r;
+        return query(0, 0, n - 1);
+    }
+};
+
+signed main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    ll n;
+    cin >> n;
+
+    ll prev = n;
+
+    if (n > 1) {
+        n = 1 << (32 - __builtin_clz(n));
+    }
+
+    segtree_arithmethic arithmethic(n);
+    segtree_sum sum(n);
+
+    char op;
+    while (cin >> op, op != 'E') {
+        if (op == 'I') {
+            int a, b, d;
+            cin >> a >> b >> d;
+
+            arithmethic.updateconst(b + 1, n, -sum.query(a, b));
+            arithmethic.updatearithmethic(a, b, d);
+            arithmethic.updateconst(a, b, sum.query(0, a - 1));
+            sum.update(a, b, d);
+            arithmethic.updateconst(b + 1, n, sum.query(a, b));
+
+            continue;
+        }
+
+        int h;
+        cin >> h;
+
+        cout << min(arithmethic.query(h), prev) << '\n';
+    }
+}
diff --git a/The 2025 ICPC South America - Brazil First Phase/H. How many teams?.cpp b/The 2025 ICPC South America - Brazil First Phase/H. How many teams?.cpp
new file mode 100644
index 0000000..0c3103f
--- /dev/null
+++ b/The 2025 ICPC South America - Brazil First Phase/H. How many teams?.cpp	
@@ -0,0 +1,152 @@
+/* Problem URL: https://codeforces.com/gym/106073/problem/H */
+
+#include <bits/stdc++.h>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/tree_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+template <class T, class comp = less<>>
+using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (int i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
+
+#define repv(i, v) for (auto &i : (v))
+#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
+#define sortv(v) sort(v.begin(), v.end())
+#define all(v) (v).begin(), (v).end()
+
+using vi = vector<int>;
+using vvi = vector<vi>;
+using vvvi = vector<vvi>;
+using vvvvi = vector<vvvi>;
+
+using ll = long long;
+
+using vl = vector<ll>;
+using vvl = vector<vl>;
+using vvvl = vector<vvl>;
+using vvvvl = vector<vvvl>;
+
+template<class v>
+auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
+    os << vec[0];
+    for (size_t i = 1; i < vec.size(); i++) {
+        os << ' ' << vec[i];
+    }
+    os << '\n';
+    return os;
+}
+
+template<class v>
+auto operator>>(istream &is, vector<v> &vec)->istream& {
+    for (auto &i : vec) {
+        is >> i;
+    }
+    return is;
+}
+
+template<class v>
+auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
+    for (auto &i : vec) {
+        os << i[0];
+        for (size_t j = 1; j < i.size(); j++) {
+            os << ' ' << i[j];
+        }
+        os << '\n';
+    }
+    return os;
+}
+
+template<class v>
+auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
+    for (auto &i : vec) {
+        for (auto &j : i) {
+            is >> j;
+        }
+    }
+    return is;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, log;
+    cin >> n >> log;
+
+    auto comb = [&](ll n, ll k) {
+        if (n < k) {
+            return 0LL;
+        }
+
+        ll ans = 1;
+        ll div = 1;
+        rep(i, k) {
+            ans *= n - i;
+            div *= (i + 1);
+        }
+
+        return ans / div;
+    };
+
+    vl sos(1 << log);
+
+    auto tobin = [&](string &a) {
+        int ans = 0;
+        repv(i, a) {
+            ans <<= 1;
+            ans += i - '0';
+        }
+
+        return ans;
+    };
+
+    vi nums(n);
+
+    rep(i, n) {
+        string fds;
+        cin >> fds;
+        nums[i] = tobin(fds);
+        sos[nums[i]]++;
+    }
+
+    rep(i, log) {
+        rep(j, 1 << log) {
+            if ((j >> i) & 1) {
+                sos[j] += sos[j ^ (1 << i)];
+            }
+        }
+    }
+
+    vl ans(1 << log);
+    rep(j, 1 << log) {
+        ans[j] = comb(sos[j], 3);
+    }
+
+    for (int i = log - 1; i >= 0; i--) {
+        for (int j = 1 << log; j >= 0; j--) {
+            if ((j >> i) & 1) {
+                ans[j] -= ans[j ^ (1 << i)];
+            }
+        }
+    }
+
+    int q;
+    cin >> q;
+    while (q--) {
+        string fds;
+        cin >> fds;
+        int now = tobin(fds);
+
+        cout << ans[now] << '\n';
+    }
+}