#include <bits/stdc++.h>

using namespace std;

vector<char> rep = {'a', 'c', 'g', 'o'};

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int n;
    cin >> n;
    string s;
    cin >> s;

    int cnt = 0;
    for (auto& ch : s)
        cnt += ch == '1';
    
    if (cnt < n*3 || cnt > 6*n){
        cout << "NIE" << "\n";
        return 0;
    }

    for (int i = 0, mini = n*3; i < n; i++, mini -= 3){
        cout << rep[min(cnt - mini, 3)];
        cnt -= 3 + min(cnt - mini, 3);
    }

    return 0;
}