#include<bits/stdc++.h>
using namespace std;
char v[] = {'a', 'i', 'u', 'e', 'o'};

bool vowel(char c){
  for (int i = 0; i < 5; i++) {
    if(v[i] == c)return true;
  }
  return false;
}

int main(int argc, char *argv[]){
  int n;
  cin >> n;
  string used[n];
  for (int i = 0; i < n; i++) {
    cin >> used[i];
  }
  string s = "inabameguru";
  if(n == 0){
    std::cout << s << std::endl;
    return 0;
  }
  sort(s.begin(), s.end());
  bool flag = false;
  do{
    bool ok = true;
    for (int i = 1; i < s.length(); i++) {
      if(!vowel(s[i -  1]) && !vowel(s[i])){
        ok = false;
        break;
      }
    }
    if(!ok || !vowel(s.back()))continue;
    flag = true;
    for (int i = 0; i < n; i++) {
      if(used[i] != s)continue;
      flag = false;
      break;
    }
    if(flag)break;
  }while(next_permutation(s.begin(), s.end()));
  if(flag)std::cout << s << std::endl;
  else std::cout << "NO" << std::endl;
  return 0;
}