diff --git a/CodeTON Round 9 (Div. 1 + Div. 2, Rated, Prizes!)/D. Shohag Loves GCD.cpp b/CodeTON Round 9 (Div. 1 + Div. 2, Rated, Prizes!)/D. Shohag Loves GCD.cpp
new file mode 100644
index 0000000..e7b3c52
--- /dev/null
+++ b/CodeTON Round 9 (Div. 1 + Div. 2, Rated, Prizes!)/D. Shohag Loves GCD.cpp	
@@ -0,0 +1,155 @@
+/* Problem URL: https://codeforces.com/problemset/problem/2039/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n, m;
+    cin >> n >> m;
+
+    vi a(m);
+    cin >> a;
+    sort(all(a), greater<>());
+
+    if (n == 1) {
+        cout << a[0] << '\n';
+        return;
+    }
+
+    if (m == 1) {
+        cout << "-1\n";
+        return;
+    }
+
+    set<int> all;
+    nrep(i, 1, n + 1) {
+        all.insert(i);
+    }
+
+    vi ans(n);
+    rep(i, m) {
+        if (all.empty()) {
+            break;
+        }
+
+        auto itr = all.begin();
+        int cur = *itr;
+        ans[*itr - 1] = a[i];
+        itr = all.erase(itr);
+
+        while (itr != all.end()) {
+            if (*itr % cur == 0) {
+                itr++;
+                continue;
+            }
+
+            ans[*itr - 1] = a[i];
+            itr = all.erase(itr);
+        }
+    }
+
+    if (!all.empty()) {
+        cout << "-1\n";
+        return;
+    }
+
+    cout << ans;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 1004 (Div. 2)/C. Devyatkino.cpp b/Codeforces Round 1004 (Div. 2)/C. Devyatkino.cpp
new file mode 100644
index 0000000..30d632d
--- /dev/null
+++ b/Codeforces Round 1004 (Div. 2)/C. Devyatkino.cpp	
@@ -0,0 +1,123 @@
+/* Problem URL: https://codeforces.com/problemset/problem/2067/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    ll n;
+    cin >> n;
+
+    rep(k, 8) {
+        string now = to_string(n - k);
+
+        int cur = 0;
+        repv(i, now) {
+            if (i <= '7') {
+                rmax(cur, i - '0');
+            }
+        }
+
+        if (k >= 7 - cur) {
+            cout << k << '\n';
+            return;
+        }
+    }
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 1040 (Div. 1)/C1. Interactive RBS (Easy Version).cpp b/Codeforces Round 1040 (Div. 1)/C1. Interactive RBS (Easy Version).cpp
new file mode 100644
index 0000000..73e62d3
--- /dev/null
+++ b/Codeforces Round 1040 (Div. 1)/C1. Interactive RBS (Easy Version).cpp	
@@ -0,0 +1,190 @@
+/* Problem URL: https://codeforces.com/problemset/problem/2129/C1 */
+
+#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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n;
+    cin >> n;
+
+    string ans(n, ' ');
+
+    vi pos(n);
+    rep(i, n) {
+        pos[i] = i + 1;
+    }
+    bool rev = false;
+
+    int total;
+    cout << "? " << n;
+    nrep(i, 1, n + 1) {
+        cout << ' ' << i;
+    }
+    cout << endl;
+    cin >> total;
+
+    if (total == 0) {
+        rev = true;
+        reverse(all(pos));
+        cout << "? " << n;
+        rep(i, n) {
+            cout << ' ' << pos[i];
+        }
+        cout << endl;
+        cin >> total;
+    }
+
+    auto sfirstclose = [&]() {
+        int low = 2;
+        int high = n;
+        int ans = 2;
+        while (low <= high) {
+            int mid = (low + high) >> 1;
+
+            cout << "? " << mid;
+            rep(i, mid) {
+                cout << ' ' << pos[i];
+            }
+            cout << endl;
+            int cur;
+            cin >> cur;
+
+            if (cur == total) {
+                ans = mid;
+                high = mid - 1;
+                continue;
+            }
+
+            low = mid + 1;
+        }
+
+        return ans;
+    };
+
+    int c = sfirstclose();
+
+    int v = pos[c -  1];
+    for (int i = 0; i + 1 < n; i += 2)  {
+        cout << "? 9 " << i + 1 << ' ' << v << ' '  << v << ' ' << i + 2 << ' ' <<  v << ' ' <<  i + 1 << ' ' << i + 1 << ' ' << i + 2 << ' ' << i + 2 << endl;
+        int cur;
+        cin >> cur;
+
+        char a1[] = {')', ')', '(', '('};
+        char a2[] = {')', '(', '(', ')'};
+
+        ans[i] = a1[cur];
+        ans[i + 1] = a2[cur];
+    }
+
+    if (n & 1) {
+        cout << "? 2 " << n << ' ' << pos[c - 1] << endl;
+        int cur;
+        cin >> cur;
+
+        if (cur == 1) {
+            ans.back() = '(';
+        } else {
+            ans.back() = ')';
+        }
+    }
+
+    cout << "! " << ans << endl;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 265 (Div. 1)/B. Restore Cube.cpp b/Codeforces Round 265 (Div. 1)/B. Restore Cube.cpp
new file mode 100644
index 0000000..a57b59b
--- /dev/null
+++ b/Codeforces Round 265 (Div. 1)/B. Restore Cube.cpp	
@@ -0,0 +1,223 @@
+/* Problem URL: https://codeforces.com/contest/464/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+struct pt {
+    ll x, y, z;
+
+    pt(ll x, ll y, ll z): x(x), y(y), z(z) {}
+    pt() = default;
+    
+    friend istream &operator >> (istream &is, pt &a) {
+        is >> a.x >> a.y >> a.z;
+        return is;
+    }
+
+    friend ostream &operator << (ostream &os, pt a) {
+        os << a.x << ' ' << a.y << ' ' << a.z;
+        return os;
+    }
+
+    pt operator ^ (pt b) {
+        return pt(y * b.z- z * b.y, z * b.x - x * b.z, x * b.y - y * b.x);
+    }
+
+    ll operator * (pt b) {
+        return x * b.x + y * b.y + z * b.z;
+    }
+
+    pt operator - (pt b) {
+        return pt(x - b.x, y - b.y, z - b.z);
+    }
+
+    bool operator == (pt b) {
+        return x == b.x && y == b.y && z == b.z;
+    }
+
+    bool operator < (pt b) {
+        if (x == b.x) {
+            if (y == b.y) {
+                return z < b.z;
+            }
+            return y < b.y;
+        }
+        return x < b.x;
+    }
+};
+
+ll dis2(pt a, pt b)
+{
+    ll x = a.x - b.x;
+    ll y = a.y - b.y;
+    ll z = a.z - b.z;
+
+    return x * x + y * y + z * z;
+}
+
+void pre()
+{
+
+}
+
+#define TEST 0
+
+void solve()
+{
+    vvi pts(8, vi(3));
+    cin >> pts;
+
+    rep(i, 8) {
+        sortv(pts[i]);
+    }
+    
+    auto check = [&](){
+        V<pt> p(8);
+        rep(i, 8) {
+            p[i] = {pts[i][0], pts[i][1], pts[i][2]};
+        }
+
+        sortv(p);
+        p.erase(unique(all(p)), p.end());
+
+        if (p.size() != 8) {
+            return false;
+        }
+
+        vi dis(7);
+        nrep(i, 1, 8) {
+            dis[i - 1] = dis2(p[i], p[0]);
+        }
+
+        sortv(dis);
+
+        nrep(i, 1, 8) {
+            vi d2;
+            rep(j, 8) {
+                if (i == j) {
+                    continue;
+                }
+
+                d2.push_back(dis2(p[i], p[j]));
+            }
+
+            sortv(d2);
+            if (d2 != dis) {
+                return false;
+            }
+        }
+
+        return true;
+    };
+
+    function<bool(int)> func = [&](int i){
+        if (i >= 8) {
+            return check();
+        }
+
+        do {
+            if (func(i + 1)) {
+                return true;
+            }
+        } while (next_permutation(all(pts[i])));
+
+        return false;
+    };
+
+    if (!func(0)) {
+        cout << "NO\n";
+        return;
+    }
+
+    cout << "YES\n";
+    cout << pts;
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 874 (Div. 3)/G. Ksyusha and Chinchilla.cpp b/Codeforces Round 874 (Div. 3)/G. Ksyusha and Chinchilla.cpp
new file mode 100644
index 0000000..bbc6355
--- /dev/null
+++ b/Codeforces Round 874 (Div. 3)/G. Ksyusha and Chinchilla.cpp	
@@ -0,0 +1,182 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1833/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n;
+    cin >> n;
+
+    V<set<pair<int, int>>> graph(n);
+
+    nrep(i, 1, n) {
+        int a, b;
+        cin >> a >> b;
+        a--, b--;
+        graph[a].emplace(b, i);
+        graph[b].emplace(a, i);
+    }
+
+    set<int> er;
+
+    bool pos = true;
+    function<int(int, int)> dfs = [&](int i, int p) {
+        int c = 0;
+        auto cur = graph[i].begin();
+        while (cur != graph[i].end()) {
+            auto [j, ind] = *cur;
+            graph[i].erase({j, ind});
+            cur = graph[i].begin();
+
+            if (graph[j].size() != 1) {
+                graph[j].erase({i, ind});
+                int res = dfs(j, ind);
+                if (res == 0) {
+                    c++;
+                    continue;
+                }
+
+                if (res == 1) {
+                    if (c != 0) {
+                        pos = false;
+                        return 2;
+                    }
+
+                    for (auto [k, _] : graph[i]) {
+                        er.insert(_);
+                        graph[k].erase({i, _});
+                        if (dfs(k, _) != 2) {
+                            pos = false;
+                            return 0;
+                        }
+                    }
+
+                    return 2;
+                }
+
+                er.insert(ind);
+                continue;
+            }
+
+            c++;
+        }
+
+        if (c > 2) {
+            pos = false;
+            return 0;
+        }
+
+        return c;
+    };
+
+    if (dfs(0, -1) != 2 || !pos) {
+        cout << "-1\n";
+        return;
+    }
+
+    er.erase(0);
+
+    cout << er.size() << '\n';
+    repv(i, er) {
+        cout << i << ' ';
+    }
+    cout << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 877 (Div. 2)/C. No Prime Differences.cpp b/Codeforces Round 877 (Div. 2)/C. No Prime Differences.cpp
new file mode 100644
index 0000000..b987541
--- /dev/null
+++ b/Codeforces Round 877 (Div. 2)/C. No Prime Differences.cpp	
@@ -0,0 +1,159 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1838/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+constexpr int MAXN = 1e6 + 10;
+bool prime[MAXN];
+
+void pre()
+{
+    fill(prime, prime + MAXN, true);
+    prime[1] = false;
+
+    nrep(i, 2, MAXN) {
+        if (!prime[i]) {
+            continue;
+        }
+
+        for (int j = i * 2; j < MAXN; j += i) {
+            prime[j] = false;
+        }
+    }
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n, m;
+    cin >> n >> m;
+
+    vvi ans(n, vi(m));
+
+    if (!prime[m]) {
+        rep(i, n) {
+            rep(j, m) {
+                ans[i][j] = i * m + j + 1;
+            }
+        }
+        cout << ans << '\n';
+        return;
+    }
+
+    if (!prime[n]) {
+        rep(j, m) {
+            rep(i, n) {
+                ans[i][j] = j * n + i + 1;
+            }
+        }
+        cout << ans << '\n';
+        return;
+    }
+
+    int cur = 1;
+    for (int i = 0; i < n; i += 2) {
+        rep(j, m) {
+            ans[i][j] = cur;
+            cur++;
+        }
+    }
+
+    for (int i = 1; i < n; i += 2) {
+        rep(j, m) {
+            ans[i][j] = cur;
+            cur++;
+        }
+    }
+
+    cout << ans << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 901 (Div. 2)/D. Jellyfish and Mex.cpp b/Codeforces Round 901 (Div. 2)/D. Jellyfish and Mex.cpp
new file mode 100644
index 0000000..8bce0a4
--- /dev/null
+++ b/Codeforces Round 901 (Div. 2)/D. Jellyfish and Mex.cpp	
@@ -0,0 +1,141 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1875/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n;
+    cin >> n;
+
+    vl a(n);
+    cin >> a;
+
+    vi c(n + 3);
+    repv(i, a) {
+        if (i > n + 1) {
+            continue;
+        }
+
+        c[i]++;
+    }
+
+    int mex = 0;
+
+    rep(i, n) {
+        if (c[i] == 0) {
+            mex = i;
+            break;
+        }
+    }
+
+    ll ans = OO;
+
+    vl dp(mex + 1, OO);
+    dp[mex] = 0;
+
+    for (int i = n; i >= 0; i--) {
+        nrep(j, i + 1, mex + 1) {
+            rmin(dp[i], dp[j] + (c[i] - 1) * j + i);
+        }
+    }
+
+    cout << dp[0] << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 925 (Div. 3)/E. Anna and the Valentine's Day Gift.cpp b/Codeforces Round 925 (Div. 3)/E. Anna and the Valentine's Day Gift.cpp
new file mode 100644
index 0000000..41b6c8d
--- /dev/null
+++ b/Codeforces Round 925 (Div. 3)/E. Anna and the Valentine's Day Gift.cpp	
@@ -0,0 +1,131 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1931/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n, m;
+    cin >> n >> m;
+
+    priority_queue<int> a;
+    int total = 0;
+    rep(i, n) {
+        string s;
+        cin >> s;
+        total += s.size();
+        int rem = 0;
+        while (s.back() == '0') {
+            s.pop_back();
+            rem++;
+        }
+        a.push(rem);
+    }
+
+    while (!a.empty()) {
+        int cur = a.top();
+        a.pop();
+        a.push(0);
+        a.pop();
+        total -= cur;
+    }
+
+    cout << (total > m ? "Sasha\n" : "Anna\n");
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 925 (Div. 3)/F. Chat Screenshots.cpp b/Codeforces Round 925 (Div. 3)/F. Chat Screenshots.cpp
new file mode 100644
index 0000000..bb02758
--- /dev/null
+++ b/Codeforces Round 925 (Div. 3)/F. Chat Screenshots.cpp	
@@ -0,0 +1,210 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1931/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n, k;
+    cin >> n >> k;
+
+    vvi p(k, vi(n));
+    cin >> p;
+
+    if (n == 1 || k == 1) {
+        cout << "YES\n";
+        return;
+    }
+
+    if (k == 2) {
+        int i1 = 1;
+        int i2 = 1;
+
+        rep(i, n) {
+            if (i1 >= n) {
+                if (p[1][i2] != p[0][0]) {
+                    cout << "NO\n";
+                    return;
+                }
+
+                continue;
+            }
+
+            if (i2 >= n) {
+                if (p[0][i1] != p[1][0]) {
+                    cout << "NO\n";
+                    return;
+                }
+
+                continue;
+            }
+
+            if (p[0][i1] == p[1][i2]) {
+                i1++;
+                i2++;
+                continue;
+            }
+
+            if (p[0][i1] == p[1][0]) {
+                i1++;
+                continue;
+            }
+
+            if (p[1][i2] == p[0][0]) {
+                i2++;
+                continue;
+            }
+
+            cout << "NO\n";
+            return;
+        }
+        
+        cout << "YES\n";
+        return;
+    }
+
+    V<bool> vis(n + 1);
+    int cur = -1;
+
+    int next = -1;
+
+    int eq = n;
+
+    nrep(i, 1, n) {
+        if (next == -1) {
+            if (p[0][i] == p[1][i] || p[0][i] == p[2][i]) {
+                cur = p[0][i];
+            } else if (p[1][i] == p[2][i]) {
+                cur = p[1][i];
+            } else {
+                cout << "NO\n";
+                return;
+            }
+        } else {
+            cur = next;
+        }
+
+        next = -1;
+        vis[cur] = true;
+        rep(j, k) {
+            if (p[j][i] != cur) {
+                if (!vis[p[j][0]]) {
+                    cout << "NO\n";
+                    return;
+                }
+
+                if (next != -1 && p[j][i] != next) {
+                    cout << "NO\n";
+                    return;
+                }
+
+                next = p[j][i];
+                continue;
+            }
+
+            if (vis[p[j][0]]) {
+                cout << "NO\n";
+                return;
+            }
+        }
+    }
+
+    cout << "YES\n";
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 927 (Div. 3)/D. Card Game.cpp b/Codeforces Round 927 (Div. 3)/D. Card Game.cpp
new file mode 100644
index 0000000..150e280
--- /dev/null
+++ b/Codeforces Round 927 (Div. 3)/D. Card Game.cpp	
@@ -0,0 +1,170 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1932/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n;
+    cin >> n;
+
+    char t;
+    cin >> t;
+
+    V<string> tmp;
+    V<string> ev;
+    rep(i, n << 1) {
+        string a;
+        cin >> a;
+
+        if (a[1] == t) {
+            ev.emplace_back(a);
+            continue;
+        }
+        tmp.emplace_back(a);
+    }
+
+    sort(all(ev), greater<>());
+    sort(all(tmp), greater<>());
+
+    repv(i, tmp) {
+        ev.emplace_back(i);
+    }
+
+    V<bool> vis(n);
+    V<pair<int, int>> ans;
+
+    function<bool(int)> func = [&](int i) {
+        if (i >= (n << 1)) {
+            return true;
+        }
+
+        if (vis[i]) {
+            return func(i + 1);
+        }
+
+        nrep(j, i + 1, (n << 1)) {
+            if (vis[j]) {
+                continue;
+            }
+
+            if ((ev[i][1] == t && ev[j][1] != t) || (ev[i][1] == ev[j][1] && ev[i][0] > ev[j][0])) {
+                vis[j] = true;
+                ans.emplace_back(j, i);
+                if (func(i + 1)) {
+                    return true;
+                }
+                vis[j] = false;
+                ans.pop_back();
+            }
+        }
+        
+        return false;
+    };
+
+    if (!func(0)) {
+        cout << "IMPOSSIBLE\n";
+        return;
+    }
+
+    repv(i, ans) {
+        cout << ev[i.first] << ' ' << ev[i.second] << '\n';
+    }
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 931 (Div. 2)/C. Find a Mine.cpp b/Codeforces Round 931 (Div. 2)/C. Find a Mine.cpp
new file mode 100644
index 0000000..3a655d3
--- /dev/null
+++ b/Codeforces Round 931 (Div. 2)/C. Find a Mine.cpp	
@@ -0,0 +1,140 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1934/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    ll n, m;
+    cin >> n >> m;
+
+    auto ask = [&](int x, int y) {
+        if (y <= 0) {
+            return 100LL;
+        }
+        cout << "? " << x << ' ' << y << endl;
+        ll ans;
+        cin >> ans;
+        return ans;
+    };
+
+    auto answer = [&](int x, int y) {
+        cout << "! " << x << ' ' << y << endl;
+    };
+
+    ll dis1 = ask(1, 1);
+    ll dis2 = ask(n, 1);
+
+    ll y = (dis1 + dis2 - n + 3) >> 1;
+    ll x = dis1 + 2 - y;
+
+    ll tmp = ask(x, y);
+    if (tmp == 0) {
+        answer(x, y);
+        return;
+    }
+
+    dis2 = ask(1, m);
+
+    x = (dis1 + dis2 - m + 3) >> 1;
+    y = dis1 + 2 - x;
+
+    answer(x, y);
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Codeforces Round 944 (Div. 4)/F. Circle Perimeter.cpp b/Codeforces Round 944 (Div. 4)/F. Circle Perimeter.cpp
new file mode 100644
index 0000000..ff94cc8
--- /dev/null
+++ b/Codeforces Round 944 (Div. 4)/F. Circle Perimeter.cpp	
@@ -0,0 +1,139 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1971/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    ll r;
+    cin >> r;
+
+    ll low = r * r;
+    ll high = (r + 1) * (r + 1);
+
+    ll x = 0;
+    ll y = 0;
+
+    auto dis = [&](ll x, ll y) {
+        return x * x + y * y;
+    };
+
+    ll ans = 0;
+
+    while (y <= r) {
+        while (dis(x + 1, y) <= low) {
+            x++;
+        }
+
+        while (dis(x, y) >= high) {
+            x--;
+        }
+
+        while (dis(x - 1, y) >= low && x > 0) {
+            ans++;
+            x--;
+        }
+
+        ans++;
+        y++;
+    }
+
+    cout << ans + (ans - 2) * 3 + 2 << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Educational Codeforces Round 162 (Rated for Div. 2)/C. Find B.cpp b/Educational Codeforces Round 162 (Rated for Div. 2)/C. Find B.cpp
new file mode 100644
index 0000000..1e2d584
--- /dev/null
+++ b/Educational Codeforces Round 162 (Rated for Div. 2)/C. Find B.cpp	
@@ -0,0 +1,130 @@
+/* Problem URL: https://codeforces.com/problemset/problem/1923/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n, q;
+    cin >> n >> q;
+
+    vl a(n);
+    cin >> a;
+
+    vi pref(n + 1);
+    vl sum(n + 1);
+
+    nrep(i, 1, n + 1) {
+        pref[i] = pref[i - 1] + (a[i - 1] == 1);
+        sum[i] += sum[i - 1] + (a[i - 1] - 1) * (a[i - 1] != 1);
+    }
+
+    while (q--) {
+        int l, r;
+        cin >> l >> r;
+
+        if (l == r || (sum[r] - sum[l - 1] < pref[r] - pref[l - 1])) {
+            cout << "NO\n";
+            continue;
+        }
+
+        cout << "YES\n";
+    }
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Educational Codeforces Round 169 (Rated for Div. 2)/D. Colored Portals.cpp b/Educational Codeforces Round 169 (Rated for Div. 2)/D. Colored Portals.cpp
new file mode 100644
index 0000000..264bde7
--- /dev/null
+++ b/Educational Codeforces Round 169 (Rated for Div. 2)/D. Colored Portals.cpp	
@@ -0,0 +1,161 @@
+/* Problem URL: https://codeforces.com/problemset/problem/2004/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;
+}
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+
+void pre()
+{
+
+}
+
+#define TEST 1
+
+void solve()
+{
+    int n, q;
+    cin >> n >> q;
+
+    int ac[256];
+    ac['R'] = 1;
+    ac['B'] = 2;
+    ac['G'] = 4;
+    ac['Y'] = 8;
+
+    vi mask(n);
+
+    vvi adj(16);
+
+    rep(i, n) {
+        string a;
+        cin >> a;
+
+        mask[i] = ac[a[0]] | ac[a[1]];
+        adj[mask[i]].push_back(i);
+    }
+
+    rep(i, 16) {
+        sortv(adj[i]);
+    }
+
+    while (q--) {
+        int a, b;
+        cin >> a >> b;
+        a--, b--;
+
+        if (mask[a] & mask[b]) {
+            cout << abs(a - b) << '\n';
+            continue;
+        }
+
+        int ans = oo;
+        int f = min(a, b);
+
+        rep(i, 16) {
+            if (__builtin_popcount(i) != 2 || (i & mask[a]) == 0 || (i & mask[b]) == 0) {
+                continue;
+            }
+
+            auto itr = upper_bound(all(adj[i]), f);
+            if (itr != adj[i].end()) {
+                rmin(ans, abs(*itr - a) + abs(*itr - b));
+            }
+
+            if (itr != adj[i].begin()) {
+                itr--;
+                rmin(ans, abs(*itr - a) + abs(*itr - b));
+            }
+        }
+
+        cout << (ans == oo ? -1 : ans) << '\n';
+    }
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/Good Bye 2017/C. New Year and Curling.cpp b/Good Bye 2017/C. New Year and Curling.cpp
new file mode 100644
index 0000000..1347396
--- /dev/null
+++ b/Good Bye 2017/C. New Year and Curling.cpp	
@@ -0,0 +1,156 @@
+/* Problem URL: https://codeforces.com/contest/908/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;
+}
+
+using ld = long double;
+
+const int oo = INT32_MAX >> 1;
+const ll OO = INT64_MAX >> 1;
+
+const ld EPS = 1e-9;
+
+struct pt {
+    ld x, y;
+
+    pt(ld x, ld y): x(x), y(y) {}
+    pt() = default;
+
+    friend istream &operator >> (istream &is, pt &a) {
+        is >> a.x >> a.y;
+        return is;
+    }
+
+    friend ostream &operator << (ostream &os, pt a) {
+        os << a.x << a.y; 
+        return os;
+    }
+};
+
+void pre()
+{
+
+}
+
+#define TEST 0
+
+void solve()
+{
+    int n;
+    int rad;
+    cin >> n >> rad;
+
+    V<pt> ans;
+
+    ld x;
+    cin >> x;
+    ans.emplace_back(pt(x, rad));
+
+    rep(i, n - 1) {
+        cin >> x;
+
+        ld l = x - rad * 2;
+        ld r = x + rad * 2;
+
+        ld y = rad;
+
+        repv(now, ans) {
+            if (now.x >= l && now.x <= r) {
+                rmax(y, now.y + sqrtl(4 * rad * rad - abs(now.x - x) * abs(now.x - x)));
+            }
+        }
+
+        ans.emplace_back(x, y);
+    }
+
+    repv(i, ans) {
+        cout << setprecision(12) << i.y << ' ';
+    }
+    cout << '\n';
+}
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    pre();
+
+    int t;
+    (TEST && cin >> t) || (t = 1);
+    while (t--) {
+        solve();
+    }
+}
diff --git a/problemlist.md b/problemlist.md
index bfc73c0..40d3a77 100644
--- a/problemlist.md
+++ b/problemlist.md
@@ -94,6 +94,10 @@ A little collection of interesting problems that I randomly decided to do.
 - [B. Jzzhu and Sequences](https://codeforces.com/contest/450/problem/B)
 
 	Basic problem about matrix exponentation, but not as obvious.
+	
+- [D. Jellyfish and Mex](https://codeforces.com/problemset/problem/1875/D)
+
+	An interesting problem to thinkm about.
 
 ## Graph