#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <climits>
#include <map>
#include <queue>
#include <set>
#include <cstring>
#include <vector>

using namespace std;
typedef long long ll;

const char A[4] = {'i', 'e', 'a', 'u'};
const char B[5] = {'n', 'b', 'm', 'g', 'r'};

map<string, bool> memo;
string ans;

void dfs(string &str, int mask, int *counter, int a_count, bool insert_flg) {
  if (str.size() == 11) {
    if (memo.count(str) == 0) {
      ans = str;
    }
    return;
  }
  if (ans.size() > 0) return;

  if (str.size() == 0 || not insert_flg) {
    for (int i = 0; i < 4; ++i) {
      if (i <= 1 && counter[i] >= 1) continue;
      if (i >= 2 && counter[i] >= 2) continue;
      str.push_back(A[i]);
      counter[i]++;

      dfs(str, mask, counter, a_count + 1, (a_count > 0 || str.size() == 1));

      str.pop_back();
      counter[i]--;
    }

    if (str.size() == 0 || a_count > 0) {
      for (int i = 0; i < 5; ++i) {
        if (mask >> i & 1) continue;
        str.push_back(B[i]);
        int nmask = mask | (1 << i);

        dfs(str, nmask, counter, 0, insert_flg);

        str.pop_back();
      }
    }
  } else if(a_count == 0) {
    for (int i = 0; i < 4; ++i) {
      if (i <= 1 && counter[i] >= 1) continue;
      if (i >= 2 && counter[i] >= 2) continue;
      str.push_back(A[i]);
      counter[i]++;

      dfs(str, mask, counter, a_count + 1, insert_flg);

      str.pop_back();
      counter[i]--;
    }
  } else {
    if (not insert_flg) {
      for (int i = 0; i < 4; ++i) {
        if (i <= 1 && counter[i] >= 1) continue;
        if (i >= 2 && counter[i] >= 2) continue;
        str.push_back(A[i]);
        counter[i]++;

        dfs(str, mask, counter, a_count + 1, true);

        str.pop_back();
        counter[i]--;
      }
    }

    for (int i = 0; i < 5; ++i) {
      if (mask >> i & 1) continue;
      str.push_back(B[i]);
      int nmask = mask | (1 << i);

      dfs(str, nmask, counter, 0, insert_flg);

      str.pop_back();
    }
  }
}


int main() {
  int N;
  cin >> N;
  for (int i = 0; i < N; ++i) {
    string s;
    cin >> s;
    memo[s] = true;
  }

  int counter[4] = {0, 0, 0, 0};
  string str = "";
  dfs(str, 0, counter, 0, false);

  if (ans.size() == 0) {
    cout << "NO" << endl;
  } else {
    cout << ans << endl;
  }

  return 0;
}