func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long n;     cin >> n;     string s;     cin >> s;     if (n % 4 != 0) {       cout <<  === ;       return 0;     }     vector<long long> v(5, 0);     for (long long i = 0; i < n; i++) {       if (s[i] ==  A ) {         v[0]++;       }       if (s[i] ==  C ) {         v[1]++;       }       if (s[i] ==  G ) {         v[2]++;       }       if (s[i] ==  T ) {         v[3]++;       }       if (s[i] ==  ? ) {         v[4]++;       }     }     long long max1 = max(v[0], max(v[1], v[2]));     long long maxov = max(max1, v[3]);     long long reqd = 4 * maxov - v[0] - v[1] - v[2] - v[3];     bool check = false;     if (v[4] >= reqd && (v[4] - reqd) % 4 == 0) {       check = true;     }     if (check == false) {       cout <<  === ;     } else {       long long reqda = maxov - v[0] + ((v[4] - reqd) / 4);       long long reqdc = maxov - v[1] + ((v[4] - reqd) / 4);       long long reqdg = maxov - v[2] + ((v[4] - reqd) / 4);       long long reqdt = maxov - v[3] + ((v[4] - reqd) / 4);       for (long long i = 0; i < n; i++) {         if (s[i] !=  ? ) {           cout << s[i];         } else {           if (reqda > 0) {             cout <<  A ;             reqda--;             continue;           }           if (reqdc > 0) {             cout <<  C ;             reqdc--;             continue;           }           if (reqdg > 0) {             cout <<  G ;             reqdg--;             continue;           }           if (reqdt > 0) {             cout <<  T ;             reqdt--;           }         }       }     }     return 0;   }   