#include <bits/stdc++.h>   using namespace std;   char A[300];   int cnt[5];   char data[5] =  ACGT ;   int main() {     int n;     scanf( %d , &n);     scanf( %s , A);     for (int i = 0; A[i]; i++) {       if (A[i] ==  A )         cnt[0]++;       else if (A[i] ==  C )         cnt[1]++;       else if (A[i] ==  G )         cnt[2]++;       else if (A[i] ==  T )         cnt[3]++;       else         cnt[4]++;     }     int big = 0, dif = 0;     ;     for (int i = 0; i < 4; i++) big = max(big, cnt[i]);     for (int i = 0; i < 4; i++) {       cnt[i] = big - cnt[i];       dif += cnt[i];     }     if (dif > cnt[4]) {       printf( === );       return 0;     }     if ((cnt[4] - dif) % 4 != 0) {       printf( === );       return 0;     }     int flag = 0;     for (int i = 0; A[i]; i++) {       if (A[i] ==  ? ) {         flag = 0;         for (int j = 0; j < 4; j++) {           if (cnt[j] > 0) {             A[i] = data[j];             cnt[j]--;             flag = 1;             break;           }         }         if (flag == 0) {           for (int j = 0; j < 4; j++) cnt[j]++;           i--;         }       }     }     printf( %s , A);   }   