#include<stdio.h>
#include<string.h>
char s[1000000] = { 0 }, t[1000000] = { 0 };
int main()
{
	scanf("%s%s", s, t);
	if (strcmp(s, t) > 0)
		printf("abcdefghijklmnopqrstuvwxyz");
	else printf("zyxwvutsrqponmlkjihgfedcba");
	return 0;
}