#include <bits/stdc++.h>

using namespace std;

int main() {
  string a = "iaaeuu", b = "nbmgr";
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  set<string> s;
  do {
    do {
      string str = a;
      for (size_t i = 0; i < b.size(); ++i) str.insert(2 * i + 1, 1, b[i]);
      s.insert(str);
    } while (next_permutation(b.begin(), b.end()));
  } while (next_permutation(a.begin(), a.end()));
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    string str;
    cin >> str;
    s.erase(str);
  }
  if (s.empty()) cout << "NO" << endl;
  else cout << *(s.begin()) << endl;
}