#include<stdio.h>
int main()
{
	int a, b;
	scanf("%d %d", &a, &b);
	int c = 0;
	while (a > 0 || b > 0)
	{
		if (a % 2 > 0)
		{
			if (b % 2 == 0)
			{
				printf("0\n");
				return 0;
			}
		}
		else
		{
			if (b % 2 > 0)
				c++;
		}
		a /= 2;
		b /= 2;
	}
	int ans = 1;
	while (c > 1)
	{
		c--;
		ans *= 2;
	}
	printf("%d\n", ans);
	return 0;
}