#include <bits/stdc++.h>

using namespace std;

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n;
    cin >> n;

    string s;
    cin >> s;

    int cnt[2] = {0, 0};
    for(auto i: s) {
        cnt[i%2]++;
    }

    cnt[0] -= 2*n;
    cnt[1] -= 3*n;

    if(cnt[0] < 0 || cnt[1] < 0) {
        cout << "NIE\n";
        return 0;
    }

    while(cnt[0] || cnt[1]) {
        if(cnt[0] >= 3 && cnt[1]  >= 0) {
            cout << "a";
            cnt[0] -= 3;
            cnt[1] -= 0;
        } else if(cnt[0] == 2 && cnt[1]  >= 1) {
            cout << "c";
            cnt[0] -= 2;
            cnt[1] -= 1;
        } else if(cnt[0] == 1 && cnt[1] >= 2) {
            cout << "g";
            cnt[0] -= 1;
            cnt[1] -= 2;
        } else if(cnt[0] == 0 && cnt[1] >= 3) {
            cout << "o";
            cnt[0] -= 0;
            cnt[1] -= 3;
        } else {
            cout << "NIE\n";
            return 0;
        }
    }
    cout << "\n";

    return 0;
}