using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Collections.Generic;
using System.Diagnostics;
using System.Numerics;
using Enu = System.Linq.Enumerable;

class Program
{
    static readonly string Name = "inabameguru";
    static readonly string Vowels = "aeiou";
    HashSet<long> BadKey = new HashSet<long>();
    string Ans = null;

    public void Solve()
    {
        int N = Reader.Int();
        var S = Reader.StringArray(N);

        foreach (var s in S)
        {
            long key = 0;
            foreach (char c in s) key = key * 27 + c - '0';
            BadKey.Add(key);
        }
        int[] count = new int[26];
        foreach (char c in Name) count[c - 'a']++;
        Rec(0, new StringBuilder(), 0, count);
        Console.WriteLine(Ans ?? "NO");
    }

    void Rec(int i, StringBuilder s, long key, int[] rem)
    {
        if (Ans != null) return;
        if (i == Name.Length)
        {
            if (Vowels.IndexOf(s[s.Length - 1]) >= 0 && !BadKey.Contains(key))
                Ans = s.ToString();
            return;
        }
        for (int c = 0; c < 26; c++)
            if (rem[c] > 0)
            {
                char use = (char)('a' + c);
                if (Vowels.IndexOf(use) < 0 && s.Length > 0 && Vowels.IndexOf(s[s.Length - 1]) < 0)
                    continue;
                var next = new StringBuilder();
                next.Append(s);
                next.Append(use);
                rem[c]--;
                Rec(i + 1, next, key * 27 + c, rem);
                rem[c]++;
            }
    }
}


class Entry { static void Main() { new Program().Solve(); } }
class Reader
{
    private static TextReader reader = Console.In;
    private static readonly char[] separator = { ' ' };
    private static readonly StringSplitOptions op = StringSplitOptions.RemoveEmptyEntries;
    private static string[] A = new string[0];
    private static int i;
    private static void Init() { A = new string[0]; }
    public static void Set(TextReader r) { reader = r; Init(); }
    public static void Set(string file) { reader = new StreamReader(file); Init(); }
    public static bool HasNext() { return CheckNext(); }
    public static string String() { return Next(); }
    public static int Int() { return int.Parse(Next()); }
    public static long Long() { return long.Parse(Next()); }
    public static double Double() { return double.Parse(Next()); }
    public static int[] IntLine() { return Array.ConvertAll(Split(Line()), int.Parse); }
    public static int[] IntArray(int N) { return Enu.Range(0, N).Select(i => Int()).ToArray(); }
    public static int[][] IntTable(int H) { return Enu.Range(0, H).Select(i => IntLine()).ToArray(); }
    public static string[] StringArray(int N) { return Enu.Range(0, N).Select(i => Line()).ToArray(); }
    public static string Line() { return reader.ReadLine().Trim(); }
    private static string[] Split(string s) { return s.Split(separator, op); }
    private static string Next() { CheckNext(); return A[i++]; }
    private static bool CheckNext()
    {
        if (i < A.Length) return true;
        string line = reader.ReadLine();
        if (line == null) return false;
        if (line == "") return CheckNext();
        A = Split(line);
        i = 0;
        return true;
    }
}