#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int main(){
	
	int a,b;
	cin>>a>>b;
	
	int ans = a|b;
	ans -= a&b;
	
	cout<<ans<<endl;
	
	return 0;
}