#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector< int > vi;
typedef vector< vi > vvi;
typedef vector< ll > vl;
typedef vector< vl > vvl;
typedef pair< int, int > pii;
typedef vector< pii > vp;
typedef vector< double > vd;
typedef vector< vd > vvd;
typedef vector< string > vs;

template< class T1, class T2 >
int upmin( T1 &x, T2 v ){
  if( x > v ){
    x = v;
    return 1;
  }
  return 0;
}

template< class T1, class T2 >
int upmax( T1 &x, T2 v ){
  if( x < v ){
    x = v;
    return 1;
  }
  return 0;
}

const int INF = 0x3f3f3f3f;

int N;
vs S;

void init(){
  cin >> N;
  S = vs( N );
  for( int i = 0; i < N; ++i )
    cin >> S[ i ];
}

set< string > dict;

void preprocess(){
  for( int i = 0; i < N; ++i )
    dict.emplace( S[ i ] );
}

void solve(){
  vi mu( 256 );
  mu[ 'a' ] = mu[ 'e' ] = mu[ 'i' ] = mu[ 'o' ] = mu[ 'u' ] = 1;
  string x = "inabameguru";
  sort( x.begin(), x.end() );
  do{
    int ng = not mu[ x[ x.size() - 1 ] ];
    for( int i = 1; i < x.size(); ++i )
      if( not mu[ x[ i - 1 ] ] and not mu[ x[ i ] ] )
        ng = 1;
    if( ng ) continue;
    if( dict.count( x ) ) continue;
    cout << x << endl, exit( 0 );
  } while( next_permutation( x.begin(), x.end() ) );
  cout << "NO" << endl;
}

signed main(){
  ios::sync_with_stdio( 0 );
  init();
  preprocess();
  solve();
  return 0;
}