100 1
1000000 100 1000
 5 3
1 4 10
2 2 5
3 1 6
 10 4
1 5 20
2 5 200
100 6 20
101 1 100
 5 3
1 3 4
4 3 4
6 4 1
 4 1
6 1 1
 8 6
1 3 20
4 2 1
6 6 5
9 1 1
15 3 6
21 8 8
 4 5
1 2 3
2 1 3
3 1 2
4 3 3
5 4 1
 8 4
1 3 2
2 3 100
10 6 20
11 5 20
 4 10
1 1 1
3 1 2
4 1 2
6 1 2
8 1 2
13 1 2
16 1 1
17 1 2
19 3 1
20 1 1
 5 3
1 4 4
4 2 2
5 5 2
 4 3
1 3 10
2 2 15
12 4 1
 5 4
1 1 4
2 4 4
5 2 20
11 5 2
 1 10
4 1 1
9 1 1
10 1 1
12 1 1
13 1 1
15 1 1
16 1 1
18 1 1
19 1 1
20 1 1

5050
 10
-1
5
 15
40
-1
1
 6
-1
10
 1
 6
9
-1
4
15
36
 3
3
4
-1
10
 6
15
-1
21
 1
1
2
1
1
1
1
1
6
1
 10
-1
15
 6
-1
10
 1
14
-1
15
 1
1
1
1
1
1
1
1
1
1

#include <bits/stdc++.h>
using namespace std;
void fil(char s[], int x, char X) {
  for (int i = 0; i < strlen(s); i++) {
    if (x > 0 && s[i] == '?') {
      s[i] = X;
      x--;
    }
    if (x == 0) break;
  }
}
int main() {
  std::ios::sync_with_stdio(0);
  int n;
  char s[1222];
  cin >> n;
  cin >> s;
  int a = 0, c = 0, g = 0, t = 0, p = 0;
  for (int i = 0; i < n; i++) {
    if (s[i] == 'A') a++;
    if (s[i] == 'C') c++;
    if (s[i] == 'G') g++;
    if (s[i] == 'T') t++;
    if (s[i] == '?') p++;
  }
  if (n % 4 != 0) {
    cout << "===";
    return 0;
  } else if ((a <= n / 4) && (c <= n / 4) && (g <= n / 4) && (t <= n / 4)) {
    int x = 0;
    x = (n / 4 - a) + (n / 4 - c) + (n / 4 - g) + (n / 4 - t);
    if (x == p) {
      fil(s, n / 4 - a, 'A');
      fil(s, n / 4 - c, 'C');
      fil(s, n / 4 - g, 'G');
      fil(s, n / 4 - t, 'T');
      cout << s;
    } else
      cout << "===";
  } else
    cout << "===";
  return 0;
}
