import java.util.*;

public class Main {
	static HashSet<String> set;
	static boolean is_boin (char a){
		if(a=='a'||a=='i'||a=='u'||a=='e'||a=='o') return true;
		return false;
	}
	static boolean check(String a){
		if( a.length()==11){
		char last_char = a.charAt(10);
		if(!is_boin(last_char)){
			return false;
		}}
		
		for(int i=0;i<a.length()-1;i++){
			if(!is_boin(a.charAt(i)) && !is_boin(a.charAt(i+1))){
				return false;
			}
		}
		return true;
	}
	static char[] moji = {'i','n','a','b','a','m','e','g','u','r','u'};//11moji
	
	static void func(String now,int used){
		if(Integer.bitCount(used)==11){
			if(!set.contains(now) && check(now)){
				System.out.println(now);
				System.exit(0);
			}else{
				return;
			}
		}
		for(int i=0;i<11;i++){
			if((used >> i & 1) == 0){
				StringBuilder aa  = new StringBuilder(now+moji[i]);
				if(!check(aa.toString())) continue;
				used+=1<<i;
				func(aa.toString(), used);
				now = aa.deleteCharAt(aa.length()-1).toString();
				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("", 0);
		System.out.println("NO");
	}
}