#include <stdio.h>
#include <string.h>

#define BMAX	(10000)
char name[] = "aaiuuebgmnr";

int character[11]={1,1,1,1,1,1,1,1,1,1,1};

int n;
int spos;
char stack[13];
char before[BMAX][13];

int saiki(int back, int depth){
	int i,j;
	int ret;
	if(depth >= 11){
		char tmp[13];
		for(i=11-1, j=0;i>=0;i--,j++){
			tmp[j] = stack[i];
			tmp[j+1] = '\0';
		}
		for(i=0;i<n;i++){
			if(strcmp(tmp, before[i]) == 0){break;}
		}
		if(i==n){
			strcpy(stack, tmp);
			return 1;
		}
		return 0;
	}
	
	for(i=0;i<11;i++){
		if(character[i] == 0){continue;}
		if(5< back && 5<i){continue;}
		
		stack[spos] = name[i];
		stack[spos+1] = '\0';
		character[i] = 0;
		spos++;
		ret = saiki(i, depth+1);
		character[i] = 1;
		
		if(ret == 1){
			break;
		}
		spos--;
		
	}
	
	return ret;
}


int main(void){
	int i;
	
	scanf("%d", &n);
	for(i=0;i<n;i++){
		scanf("%s", before[i]);
	}
	
	for(i=0;i<6;i++){
		int ret;
		stack[spos] = name[i];
		stack[spos+1] = '\0';
		spos++;
		character[i] = 0;
		ret = saiki(0, 1);
		if(ret == 1){
			break;
		}
		spos--;
		character[i] = 1;
	}
	
	printf("%s\n", stack);
	return 0;
}