import java.util.*;

public class Main {
    static HashSet<String> set;

    static boolean is_vowel(char a) {
        if (a == 'a' || a == 'i' || a == 'u' || a == 'e' || a == 'o') return true;
        return false;
    }


    static char[] moji = {'i', 'n', 'a', 'b', 'a', 'm', 'e', 'g', 'u', 'r', 'u'};//11moji

    static void func(char[] now, int current, int used) {
        if (current == 11) {
            if (!set.contains(new String(now))) {
                System.out.println(now);
                System.exit(0);
            } else {
                return;
            }
        }
        for (int i = 0; i < 11; i++) {
            if ((used >> i & 1) == 0) {
//                if (((used >> 2 & 1) == 0 && (used >> 4 & 1) > 0) || ((used >> 8 & 1) == 0 && (used >> 10 & 1) > 0))
//                    return;
                if ((used & 0b10101010101) == 0b10101010101) {
                    return;
                }
                now[current] = moji[i];
                if (current > 0) {
                    if (!is_vowel(now[current - 1]) && !is_vowel(now[current])) {
                        continue;
                    }
                }
                used += 1 << i;
                func(now, current + 1, used);
                used -= 1 << i;
            }
        }
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        set = new HashSet<>();
        for (int i = 0; i < N; i++) set.add(sc.next());
        func(new char[11], 0, 0);
        System.out.println("NO");
    }
}