func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m, ans;   int G[10][10];   int p[10];   bool vis[10][10];   void dfs(int cur) {     if (cur > n) {       memset(vis, 0, sizeof(vis));       int cnt = 0;       for (int i = 1; i <= n; i++) {         for (int j = i + 1; j <= n; j++) {           if (!G[i][j]) continue;           int u = p[i];           int v = p[j];           if (!vis[u][v]) {             vis[u][v] = vis[v][u] = true;             cnt++;           }         }       }       ans = max(ans, cnt);       return;     }     for (int i = 1; i <= 6; i++) {       p[cur] = i;       dfs(cur + 1);     }   }   int main() {     scanf( %d%d , &n, &m);     for (int i = 0; i < m; i++) {       int u, v;       scanf( %d%d , &u, &v);       G[u][v] = G[v][u] = 1;     }     dfs(1);     printf( %d n , ans);     return 0;   }   