func_code_string: #include <bits/stdc++.h>   using namespace std;   int a[300005];   int b[300005];   int flag;   int main() {     int n, m;     cin >> n >> m;     int i = 0, j = 0;     for (i = 0; i < m; i++) {       cin >> a[i];       cin >> b[i];       j++;     }     int hh = a[0], ff = b[0];     int cc, fff;     int temp = 0;     for (int i = 0; i < m; i++) {       if (a[i] == hh || b[i] == ff || a[i] == ff || b[i] == hh)         continue;       else {         temp = 1;         cc = a[i];         fff = b[i];         break;       }     }     if (temp == 0) {       printf( YES );       return 0;     }     int sum = 0;     for (int i = 0; i < m; i++) {       if ((a[i] != hh && b[i] != hh) && (a[i] != cc && b[i] != cc)) sum++;     }     if (sum == 0) {       printf( YES );       return 0;     }     sum = 0;     for (int i = 0; i < m; i++) {       if ((a[i] != hh && b[i] != hh) && (a[i] != fff && b[i] != fff)) sum++;     }     if (sum == 0) {       printf( YES );       return 0;     }     sum = 0;     for (int i = 0; i < m; i++) {       if ((a[i] != ff && b[i] != ff) && (a[i] != cc && b[i] != cc)) sum++;     }     if (sum == 0) {       printf( YES );       return 0;     }     sum = 0;     for (int i = 0; i < m; i++) {       if ((a[i] != ff && b[i] != ff) && (a[i] != fff && b[i] != fff)) sum++;     }     if (sum == 0) {       printf( YES );       return 0;     }     if (sum != 0) printf( NO );   }   