#include<stdio.h>
int main()
{
	char a[64], b[64];
	int i;
	scanf("%s%s", a, b);
	int x, y;
	x = y = 0;
	for (i = 0; a[i] != '\0'; i++)
		x = 2 * x + a[i] - '0';
	for (i = 0; b[i] != '\0'; i++)
		y = 2 * y + b[i] - '0';
	printf("%d\n", x ^ y);
	return 0;
}