func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, m;     map<int, vector<int>> mappu;     cin >> n >> m;     for (long long i = (0); i < (m); i++) {       int a, b;       cin >> a >> b;       mappu[a].push_back(b);       mappu[b].push_back(a);     }     for (long long i = (1); i < (n + 1); i++) {       mappu[i].push_back(i);       sort(mappu[i].begin(), mappu[i].end());     }     for (long long i = (1); i < (n + 1); i++) {       for (long long j = (0); j < (mappu[i].size()); j++) {         if (mappu[i] != mappu[mappu[i][j]]) {           cout <<  NO ;           return 0;         }       }     }     cout <<  YES ;   }   