#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <math.h>
using namespace std;
typedef long long int ll;

int main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	ll a,b; cin >> a >> b;
	ll k=(a|b);
	if(k!=b||a>b){
		cout << 0 << endl;
		return 0;
	}
	int n=__builtin_popcountll(b)-__builtin_popcountll(a);
	cout << (ll)pow(2,n)/2 << endl;
}