func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int T = 1;     while (T--) {       int n, m;       cin >> n >> m;       map<int, int> mp;       vector<pair<int, int> > pp;       for (int i = 0; i < m; i++) {         int a, b;         cin >> a >> b;         pp.push_back({a, b});         if (a != b) {           mp[a]++;           mp[b]++;         } else           mp[a]++;       }       vector<pair<int, int> > maxi;       for (auto x : mp) {         maxi.push_back({x.second, x.first});       }       sort(maxi.rbegin(), maxi.rend());       int mm = min(4, int((maxi).size()));       for (int q = 0; q < mm; q++) {         vector<int> v(m, 0);         int cnt = 0;         for (int i = 0; i < m; i++) {           if (pp[i].first == maxi[q].second || pp[i].second == maxi[q].second) {             v[i] = 1;             cnt++;           }         }         cnt = m - cnt;         if (cnt == 0) {           cout <<  YES ;           exit(0);         }         mp.clear();         for (int i = 0; i < m; i++) {           if (v[i] == 0) {             if (pp[i].first != pp[i].second) {               mp[pp[i].first]++;               mp[pp[i].second]++;             } else               mp[pp[i].first]++;           }         }         for (auto x : mp) {           if (x.second == cnt) {             cout <<  YES ;             exit(0);           }         }       }       cout <<  NO ;     }     return 0;   }   