func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m, f, t;   const int N = 1e3 + 5;   vector<int> adj[N];   int col[N], vis[N], row[N];   int dj[N][N];   int mn = -1e9, id = 1;   void dfs(int u, int ret) {     if (u == n + 1) {       ret = 0;       for (int i = 1; i <= 6; i++) {         for (int j = i; j <= 6; j++) {           dj[i][j] = 0;         }       }       for (int i = 1; i <= n; i++) {         for (auto j : adj[i]) {           int c = col[i];           int k = col[j];           if (!dj[c][k] && c <= k) {             ret++;             dj[c][k] = 1;           }         }       }       mn = max(mn, ret);       return;     }     for (int i = 1; i <= 6; i++) {       if (!col[u]) {         col[u] = i;         dfs(u + 1, 0);         col[u] = 0;       }     }   }   int main() {     cin >> n >> m;     while (m--) {       cin >> f >> t;       adj[f].push_back(t);       adj[t].push_back(f);     }     dfs(1, 1);     cout << mn <<   n ;   }   