#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
signed main(){
  int n;
  cin>>n;
  set<string> ss;
  for(int i=0;i<n;i++){
    string s;
    cin>>s;
    ss.emplace(s);
  }
  
  string b="inabameguru";
  sort(b.begin(),b.end());
  auto is_b=[](char c){return c=='a'||c=='i'||c=='u'||c=='e'||c=='o';};
  do{
    if(ss.count(b)) continue;
    if(!is_b(b.back())) continue;
    int flg=0;
    for(int i=0;i+1<(int)b.size();i++)
      flg|=!is_b(b[i])&&!is_b(b[i+1]);
    if(flg) continue;
    cout<<b<<endl;
    return 0;
  }while(next_permutation(b.begin(),b.end()));
  
  cout<<"NO"<<endl;
  return 0;
}