#include <iostream>
#include <bitset>
//にゃー
using namespace std;
int main(){
	int a,b;cin>>a>>b;
	bitset<32> A(a),B(b);
	//cout << A << endl;
	//cout << B << endl;
	long long z = 1;
	for(int i = 0; 32 > i; i++){
		if(A[i] && !B[i]){
			cout << 0 << endl;
			return 0;
		}else if(!A[i] && B[i]){
			z*=2;
		}
	}
	if(z==1)cout << z << endl;
	else cout << z/2 << endl;
}