#include <iostream>
#include <cstring>
#include <cmath>
using namespace std;

int main(){
	int n;
	string s;
	cin >> n;
	cin >> s;
	int c = 0;
	for (int i = 0; i < 8 * n; i++){
		if (s[i] == '1'){
			c++;
		}
	}
	double ratio = (double)c / n;
	double w = ratio - (int)ratio;
	w *= n;
	int la = round(w);
	if ((ratio < 3) || (ratio > 6)){
		cout << "NIE\n";
		return 0;
	}
	char let[8];
	let[3] = 'a';
	let[4] = 'c';
	let[5] = 'g';
	let[6] = 'w';
	int bits_used = 0;
	//cout << ratio << " " << w << " " << round(w) << " " << la << "\n";
	for (int i = 0; i < la; i++){
		cout << let[(int)ratio + 1];
		bits_used += (int)ratio + 1;
	}
	for (int i = la; i < n - 1; i++){
		cout << let[(int)(ratio)];
		bits_used += (int)ratio;
	}
	if (la < n){
		//cout << c << " " << bits_used << "\n";
		cout << let[c - bits_used];
	}
}