#include <bits/stdc++.h>
#define EPS 1e-9
#define INF 1070000000LL
#define MOD 1000000007LL
#define fir first
#define foreach(it,X) for(auto it=(X).begin();it!=(X).end();it++)
#define numa(x,a) for(auto x: a)
#define ite iterator
#define mp make_pair
#define rep(i,n) rep2(i,0,n)
#define rep2(i,m,n) for(int i=m;i<(n);i++)
#define pb push_back
#define pf push_front
#define sec second
#define sz(x) ((int)(x).size())
#define ALL( c ) (c).begin(), (c).end()
#define gcd(a,b) __gcd(a,b)
#define mem(x,n) memset(x,n,sizeof(x))
#define endl "\n"
using namespace std;
template <int POS, class TUPLE> void deploy(std::ostream &os, const TUPLE &tuple){}
template <int POS, class TUPLE, class H, class ...Ts> void deploy(std::ostream &os, const TUPLE &t){ os << (POS == 0 ? "" : ", ") << get<POS>(t); deploy<POS + 1, TUPLE, Ts...>(os, t); }
template <class T,class U> std::ostream& operator<<(std::ostream &os, std::pair<T,U> &p){ os << "(" << p.first <<", " << p.second <<")";return os; }
template <class T> std::ostream& operator<<(std::ostream &os, std::vector<T> &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "}" : ", "); return os; }
template <class T> std::ostream& operator<<(std::ostream &os, std::set<T> &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "}" : ", "); return os; }
template <class T, class K> std::ostream& operator<<(std::ostream &os, std::map<T, K> &mp){ int remain = mp.size(); os << "{"; for(auto e: mp) os << "(" << e.first << " -> " << e.second << ")" << (--remain == 0 ? "}" : ", "); return os; }
#define DEBUG1(var0) { std::cerr << (#var0) << "=" << (var0) << endl; }
#define DEBUG2(var0, var1) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG1(var1); }
#define DEBUG3(var0, var1, var2) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG2(var1,var2); }
#define DEBUG4(var0, var1, var2, var3) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG3(var1,var2,var3); }
using ll = long long;
const string vowels = "aiueo";
inline bool OK(string &s){
  bool vowel = vowels.find(s[0]) != string::npos;
  rep2(i,1,sz(s)){
    if (vowel) {
      vowel = vowels.find(s[i]) != string::npos;
    }else{
      vowel = vowels.find(s[i]) != string::npos;
      if (!vowel) {
        return false;
      }
    }
  }
  return vowels.find(s.back()) != string::npos;
}

int main()
{
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  string S1 = "iaaeuu";
  string S2 = "nbmgr";
  set <string> memo;
  sort(ALL(S1));

  do{
    sort(ALL(S2));
    do{
      string s;
      rep(i,5){
        s += S2[i];
        s += S1[i];
      }
      rep(i,6){
        string t;
        t += s.substr(0,i*2);
        t += S1.back();
        t += s.substr(i*2);
        memo.insert(t);
      }
    }while(next_permutation(ALL(S2)));
  }while(next_permutation(ALL(S1)));
  //DEBUG1(memo);
  DEBUG1(sz(memo));
  int N;
  cin >> N;
  rep(i,N){
    string s;
    cin >> s;
    if (memo.find(s) != memo.end()) {
      memo.erase(s);
    }
  }
  if (sz(memo) > 0) {
    cout << *memo.begin() << endl;
  }else{
    cout << "NO\n";
  }
  return 0;
}