#include<iostream>
#define rep(i,n) for(i=0;i<(int)(n);i++)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;

ll a,c;

int main(){
    scanf("%lld%lld",&a,&c);
    printf("%lld\n",(a&c)^(a|c));
    return 0;
}