#include <algorithm>
#include <array>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include<complex>
#include <cmath>
#include <iostream>
#include <fstream>
#include <queue>
#include <list>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <string>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
//#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;

char nameChars[11] = {'i','a','a','e','u','u','n','b','m','g','r'};
char ans[11];
bool used[11]; 
set<string> usedNames;



bool judge()
{
    bool beforeBoin = false;
    rep(i,11)
    {
        REP(j,11-5,11)
        {
            if (ans[i] == nameChars[j])
            {
                if (i == 10)return false; //name no saigo ga siin
                if (beforeBoin) return false;
                else beforeBoin = true;
                goto SKIP_I;
            }
        }
        beforeBoin = false;
SKIP_I:;
    }
    return usedNames.find(ans) == usedNames.end();
}

bool f_find(int count)
{
    if (count == 11)
    {
        return judge();
    }

    rep(i,11)
    {
        if (!used[i])
        {
            ans[count] = nameChars[i];
            used[i] = true;
            if (f_find(count+1))
            {
                return true;
            }
            used[i] = false;
            ans[count] = NULL;
        }
    }
    return false;
}

int main()
{
    int n;
    string tmp;
    cin >> n;
    rep(i,n)
    {
        cin >> tmp;
        usedNames.insert(tmp);
    }
    if (f_find(0))
    {
        cout << ans << endl;
    }
    else
        cout << "NO" << endl;
    return 0;
}