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

int main()
{
	int A,B; cin>>A>>B;
	int cnt=0;
	for(int i=0;i<31;i++){
		int a=A>>i&1;
		int b=B>>i&1;
		if(a==1 and b==0){
			cout<<0<<endl;
			return 0;
		}
		if(a==0 and b==1) cnt++;
	}
	if(cnt==0) cout<<1<<endl;
	else cout<<(1<<(cnt-1))<<endl;
	return 0;
}