func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 4005;   vector<int> v[maxn];   int vis[maxn][maxn];   int main(void) {     int n, m, ans = maxn;     memset(vis, 0, sizeof(vis));     scanf( %d%d , &n, &m);     for (int i = 0; i < m; i++) {       int x, y;       scanf( %d%d , &x, &y);       v[x].push_back(y);       v[y].push_back(x);       vis[x][y] = vis[y][x] = 1;     }     for (int i = 1; i <= n; i++) {       for (int j = i + 1; j <= n; j++) {         if (!vis[i][j]) continue;         for (int k = j + 1; k <= n; k++) {           if (!vis[i][k] || !vis[k][j]) continue;           int cur = 0;           int len = v[i].size();           for (int d = 0; d < len; d++) {             if (v[i][d] != j && v[i][d] != k) cur++;           }           len = v[j].size();           for (int d = 0; d < len; d++) {             if (v[j][d] != i && v[j][d] != k) cur++;           }           len = v[k].size();           for (int d = 0; d < len; d++) {             if (v[k][d] != i && v[k][d] != j) cur++;           }           ans = min(ans, cur);         }       }     }     if (ans == maxn)       printf( -1 n );     else       printf( %d n , ans);   }   