#include<stdio.h>

int main(void){
	
	long long int a, b = 0, c;
	long long int i = 1;
	
	scanf("%ld%ld", &a, &c);

	while(a != 0 || c != 0){
		b += ((a % 2 + c % 2) % 2) * i;
		a /= 2;
		c /= 2;
		i *= 2;
	}
	
	printf("%ld\n", b);
	
	return 0;
}