#include <bits/stdc++.h>
#include <regex>
using namespace std;
using ll = int64_t;
#define all(c) c.begin(),c.end()
#define rall(c) c.rbegin(),c.rend()

// -------------------------------
// 2022/5/20 Hiroyuki Yamanouchi
// AtCoder Rating 187 10級
// -------------------------------

// void chmax(ll& a, ll b){ if(a < b) a = b; }
// void chmin(ll& a, ll b){ if(a > b) a = b; }
// for (int i = 0; i < N; i++){    
//      cin >> P[i];
// }


int main() {
 
    int n;
    string s;
    cin >> n >> s;

    int cnt = 1;

    while (cnt > 0){

        if (cnt > 0) cnt = 0;

        string t = s;
        int L = t.size();

        for (int i = 0; i < L; i++){   
            if (t[i] == 'A') cnt++;
            else if (t[i] == 'G') cnt++;
            else if (t[i] == 'C') cnt++;
            else if (t[i] == 'G') cnt++;
            else continue;
        }

        if (cnt == 0) {
            cout << t << endl;
            return 0;
        }

        s = "";
        for (int i = 0; i < L; i++){
            if (i != cnt) {
            s = s + t[i];
            }
            else continue;
        }

    }

    return 0;
}