func_code_string: #include <bits/stdc++.h>   using namespace std;   vector<int> v[10];   int n, ans, m, tmp;   vector<int> v2;   void recur(int now) {     if (now == n) {       int vis[7][7];       memset(vis, 0, sizeof(vis));       int ans2 = 0;       for (int e = 1; e <= n; e++) {         for (int p = 0; p < v[e].size(); p++) {           int next = v[e][p];           int f = v2[e - 1], s = v2[next - 1];           if (f > s) swap(f, s);           if (vis[f][s] == 0) {             vis[f][s] = 1;             ans2++;           }         }       }       ans = max(ans, ans2);     } else {       for (int p = 1; p <= min(n, 6); p++) {         v2.push_back(p);         recur(now + 1);         v2.pop_back();       }     }   }   int main(void) {     scanf( %d%d , &n, &m);     for (int e = 0; e < m; e++) {       int a, b;       scanf( %d%d , &a, &b);       v[a].push_back(b);       v[b].push_back(a);     }     recur(0);     printf( %d , ans);     return 0;   }   