#include <iostream>
#include <algorithm>
#include <functional>
#include <string>
#include <climits>
#include <vector>
#include <numeric>
#include <complex>
#include <map>
#include <bitset>
using namespace std;

//#define __int64 long long
#define long __int64
#define REP(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
const int Vecy[4] = {0,-1,0,1};
const int Vecx[4] = {1,0,-1,0};


int main(){
	int n;
	vector<pair<string,string> > s;
	vector<string> s2;
	string in;
	string d1,d2;
	string data = "inabameguru";
	string data1 = "aaeiuu";
	string data2 = "bgmnr";
	string check;
	string c = "aaaaaa";
	char check1[6] = {'a','a','e','i','u','u'};
	char check2[5] = {'b','g','m','n','r'};
	bool flg = true;
	
	cin >> n;
	for(int i=0; i<n; i++){
		cin >> in;
		d1 = "";
		d2 = "";
		for(int ii=0; ii<5; ii++){
			d1 += in[ii*2];
			d2 += in[ii*2+1];
		}
		d1 += in[10];
		
		s.push_back( make_pair(d1, d2) );
		s2.push_back(in);
	}
	
	sort(s.begin(), s.end());
	sort(s2.begin(), s2.end());
	int cnt = 0;
	
	
	do{
		for(int i=0; i<5; i++){
			check2[i] = data2[i];
		}
		
		do{
			flg = false;
			vector< pair<string,string> >::iterator itr = s.begin();
			for(int i=0; i<cnt; i++){
				itr ++;
			}
			
			for(int i=0; i<5; i++){
				if(check2[i] != itr->second[i]){
					flg = true;
					break;
				}
			}

			
			if(flg){
				for(int i=0; i<5; i++){
					cout << check1[i];
					cout << check2[i];
				}
				cout << check1[5] << endl;
			}
			cnt ++;
		
		}while( next_permutation(check2, check2 + 5) && !flg);
	}while( next_permutation(check1, check1 + 6) && !flg);
	
    if(!flg){
		cout << "NO" << endl;
    }
    return 0;
}