func_code_string: #include <bits/stdc++.h>   using namespace std;   bool mat[3001][3001];   vector<int> v[3010];   int main() {     int n, m, a, b, result = 0;     cin >> n >> m;     for (int i = 1; i <= n; i++)       for (int j = 1; j <= n; j++) mat[i][j] = false;     for (int i = 0; i < m; i++) {       cin >> a >> b;       v[a].push_back(b);       mat[a][b] = true;     }     for (int i = 1; i <= n; i++) {       for (int j = 1; j <= n; j++) {         if (i != j) {           int r = 0;           for (int k = 0; k < v[i].size(); k++) {             if (mat[v[i][k]][j] == true) r++;           }           result += (r * (r - 1)) / 2;         }       }     }     cout << result;   }   