func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 4005;   int tk[N][2];   int n, m;   bool r[N][N];   int deg[N];   int main() {     ios_base::sync_with_stdio(0);     cin >> n >> m;     int a, b;     for (int i = 1; i <= n; ++i) {       deg[i] = -2;       ;       for (int j = 1; j <= n; ++j) r[i][j] = false;     }     for (int i = 1; i <= m; ++i) {       cin >> a >> b;       tk[i][0] = a;       tk[i][1] = b;       r[a][b] = true;       r[b][a] = true;       ++deg[a];       ++deg[b];     }     int res = 1000000000;     int c, d;     for (int i = 1; i < m; ++i) {       for (int j = i + 1; j <= m; ++j) {         a = tk[i][0];         b = tk[i][1];         c = tk[j][0];         d = tk[j][1];         if (a == c) {           if (r[b][d]) {             res = min(res, deg[a] + deg[b] + deg[d]);           }         }         if (b == c) {           if (r[a][d]) {             res = min(res, deg[a] + deg[b] + deg[d]);           }         }         if (a == d) {           if (r[b][c]) {             res = min(res, deg[a] + deg[b] + deg[c]);           }         }         if (b == d) {           if (r[a][c]) {             res = min(res, deg[a] + deg[b] + deg[c]);           }         }       }     }     if (res == 1000000000)       cout <<  -1 n ;     else       cout << res <<   n ;   }   