func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, m;     cin >> n >> m;     string a;     vector<string> v, b;     bool u = false, l = false;     for (int i = 0; i < 4 * n; i++) {       cin >> a;       int k = 0;       u = false;       for (int j = (int)a.length() - 1; j >= 0; j--) {         if (a[j] ==  a  || a[j] ==  e  || a[j] ==  i  || a[j] ==  o  ||             a[j] ==  u )           k++;         if (k >= m) {           v.push_back(a.substr(j));           u = true;           break;         }       }       if (!u) {         l = true;       }     }     if (l) {       cout <<  NO ;       return 0;     }     for (int i = 0; i < n; i++) {       if (v[i * 4] == v[i * 4 + 1] && v[i * 4 + 1] == v[i * 4 + 2] &&           v[i * 4 + 2] == v[i * 4 + 3]) {         continue;       }       if (v[i * 4] == v[i * 4 + 1] && v[i * 4 + 2] == v[i * 4 + 3]) {         b.push_back( aabb );         continue;       }       if (v[i * 4 + 0] == v[i * 4 + 3] && v[i * 4 + 1] == v[i * 4 + 2]) {         b.push_back( abba );         continue;       }       if (v[i * 4 + 0] == v[i * 4 + 2] && v[i * 4 + 1] == v[i * 4 + 3]) {         b.push_back( abab );         continue;       }       cout <<  NO ;       return 0;     }     if ((int)b.size() == 0) {       cout <<  aaaa ;       return 0;     }     bool h = true;     for (int i = 1; i < (int)b.size(); i++) {       if (b[i] != b[i - 1]) {         h = false;         break;       }     }     if (h)       cout << b[0];     else       cout <<  NO ;     return 0;   }   