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

int main() {
    long a,b,cur,i,ans;
    cin >> a >> b;
    cur=0;
	if(a>b){
		cout << 0 << endl; return 0;
	}
    
    for(i=0; (1<<i)<=b; i++){
    	if(((1<<i) & a)&& !((1<<i) & b)){
    		cout << 0 << endl; return 0;
    	}
    	if((1<<i) & b-a){
    		cur++;
    	}
    }
    if(cur==0){
    	cout << 0 << endl;
    }else{
    	ans=1;
    	for(i=1; i<cur; i++){
    		ans*=2;
    	}
    	cout << ans << endl;
    }
    return 0;
}