// Patryk Jędrzejczak

#include <bits/stdc++.h>

using namespace std;

#define REP(i, n) for(int i = 0; i < n; ++i)
#define REPR(i, n) for(int i = n - 1; i >= 0; --i)
#define FOR(i, a, b) for(int i = a; i < b; ++i)
#define FORR(i, a, b) for(int i = b - 1; i >= a; --i)
#define EB emplace_back
#define MP make_pair
#define ST first
#define ND second
#define S size
#define RS resize
#define endl '\n'
#define L long long

template<class T> using V = vector<T>;

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);

  char ch3 = 'a', ch4 = 'c', ch5 = 'g', ch6 = 'o';

  int n;
  string s;
  cin >> n >> s;

  int ones = 0;
  REP(i, 8 * n) {
    ones += s[i] - '0';
  }

  if (ones < 3 * n || ones > 6 * n) {
    cout << "NIE";
  }
  else {
    REP(i, n) {
      if (ones - 6 >= 3 * (n - i - 1)) {
        cout << ch6;
        ones -= 6;
      }
      else if (ones - 5 >= 3 * (n - i - 1)) {
        cout << ch5;
        ones -= 5;
      }
      else if (ones - 4 >= 3 * (n - i - 1)) {
        cout << ch4;
        ones -= 4;
      }
      else {
        cout << ch3;
        ones -= 3;
      }
    }
  }
}