/* -*- coding: utf-8 -*-
 *
 * 233.cc: No.233 めぐるはめぐる (3) - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

// inabameguru

const char sos[6] = { '-', 'g', 'n', 'b', 'm', 'r' };
const char bos[6] = { 'a', 'a', 'i', 'u', 'u', 'e' };

typedef long long ll;
const ll P0 = 4561, P1 = 5347;
const ll MOD0 = 1000000007, MOD1 = 1000000009;

/* typedef */

typedef vector<string> vs;
typedef map<ll,int> mli;

/* global variables */

int sis[6], bis[6];
mli rhm0, rhm1;

/* subroutines */

void rhash(string &s, ll &rh0, ll &rh1) {
  rh0 = rh1 = 0;
  for (int i = 0; i < s.size(); i++) {
    rh0 = (rh0 * P0 % MOD0 + s[i]) % MOD0;
    rh1 = (rh1 * P1 % MOD1 + s[i]) % MOD1;
  }
}

/* main */

int main() {
  int n;
  cin >> n;

  if (n == 129600) {
    puts("NO");
    return 0;
  }
  
  vs sns;
  
  for (int i = 0; i < n; i++) {
    string s;
    cin >> s;
    sns.push_back(s);
    ll rh0, rh1;
    rhash(s, rh0, rh1);
    rhm0[rh0] = i;
    rhm1[rh1] = i;
  }

  for (int i = 0; i < 6; i++) sis[i] = bis[i] = i;

  do {
    do {
      string s;
      for (int i = 0; i < 6; i++) {
	if (sos[sis[i]] != '-') s += sos[sis[i]];
	s += bos[bis[i]];
      }

      ll rh0, rh1;
      rhash(s, rh0, rh1);

      mli::iterator mit0 = rhm0.find(rh0);
      if (mit0 == rhm0.end() || sns[mit0->second] != s) {
	mli::iterator mit1 = rhm1.find(rh1);
	if (mit1 == rhm1.end() || sns[mit1->second] != s) {
	  cout << s << endl;
	  return 0;
	}
      }
    } while (next_permutation(bis, bis + 6));
  } while (next_permutation(sis, sis + 6));
  
  return 0;
}