diff --git a/2018 ACM-ICPC, Universidad Nacional de Colombia Programming Contest/C. Cryptography.cpp b/2018 ACM-ICPC, Universidad Nacional de Colombia Programming Contest/C. Cryptography.cpp
new file mode 100644
index 0000000..27432b6
--- /dev/null
+++ b/2018 ACM-ICPC, Universidad Nacional de Colombia Programming Contest/C. Cryptography.cpp	
@@ -0,0 +1,117 @@
+/* Problem URL: https://codeforces.com/gym/101845/problem/C */
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+#define V vector
+
+#define rmin(a, b) a = min(a, b)
+#define rmax(a, b) a = max(a, b)
+
+#define rep(i, lim) for (size_t i = 0; i < (lim); i++)
+#define nrep(i, s, lim) for (size_t 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 SIZE = 127;
+
+int main()
+{
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    string a, b;
+    cin >> a >> b;
+
+    int n;
+    cin >> n;
+
+    vvl floyd(SIZE, vl(SIZE, INT64_MAX >> 1));
+
+    for (size_t i = 0; i < SIZE; i++) {
+        floyd[i][i] = 0;
+    }
+
+    while (n--) {
+        char a, b;
+        ll c;
+        cin >> a >> b >> c;
+        rmin(floyd[a][b], c);
+    }
+
+    for (size_t k = 0; k < SIZE; k++) {
+        for (size_t i = 0; i < SIZE; i++) {
+            for (size_t j = 0; j < SIZE; j++) {
+                rmin(floyd[i][j], floyd[i][k] + floyd[k][j]);
+            }
+        }
+    }
+
+    ll cost = 0;
+    for (size_t i = 0; i < a.size(); i++) {
+        if (floyd[a[i]][b[i]] == INT64_MAX >> 1) {
+            cout << "-1\n";
+            return 0;
+        }
+
+        cost += floyd[a[i]][b[i]];
+    }
+
+    cout << cost << '\n';
+}