#include <bits/stdc++.h>
using namespace std;


int main() {
	ios_base::sync_with_stdio(0);
	int n;
	cin >> n;
	string c;
	cin >> c;
	int z[2] = {0,0};
	for (int i=0;i<n*8;i++)
		z[c[i]-48]++;
	z[1] -= 2*n;
	if (z[1]<n || z[1]>4*n)
		cout << "NIE";
	else {
		string s="",codes=" acgo";
		int w = z[1]/n;
		int r = z[1]-w*n;
		//cout << w << " " << r << endl;
		for (int i=0;i<n;i++) {
			char a = codes[w+(i<r)];
			s += a;
		}
		cout << s;
	}
	return 0;
}