#include<bits/stdc++.h>
using namespace std;

int main() {
	int a,b,c,d,e,f;
	cin>>a>>b;
	c=a&b;
	d=a^b;
	while(c)
	{
		e=d;
		f=c<<1;
		c=e&f;
		d=e^f;
	}
	cout<<d;
	return 0;
}