#include <bits/stdc++.h>

#define endl '\n'
#define LL long long
#define fi first
#define sc second
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int N;
    cin >> N;       // 5z3j, 4z4j, 3z5j, 2z6j
    int dL = 0;     // + 1 , = 0 , - 1 , - 2
    string a;
    cin >> a;
    for(int i = 0; i < 8*N; i++){
        if(a[i] == '1') dL++;
        else dL--;
    }
    //cout << dL << endl;
    string Result = "";
    while(N > 0){
        if(dL == 0) Result += 'c';
        else if(dL < 0){
            Result += 'a';
            dL+=2;
        }
        else if(dL == 2){
            Result += 'g';
            dL -= 2;
        }
        else{
            Result += 'w';
            dL -= 4;
        }
        N -= 1;
    }
    if(dL != 0){
        cout << "NIE" << endl;
    }
    else{
        cout << Result << endl;
    }
    return 0;
}