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

int main() {
    ll a,b;
    std::cin >> a>>b;
    
    ll res = 0;
    for (int i = 0; i < 32; i++) {
        if( (a & (1<<i) ) && !(b & (1<<i) ) ){
            std::cout << 0 << std::endl;
            return 0;
        } 
        if( (a & (1<<i) ) ^ (b & (1<<i) ) ) {
            res++;
        }
    }
    if(a==b){
        std::cout << 1 << std::endl;
        return 0;
    }
    std::cout <<setprecision(20)<< floor(pow(2,res-1)) << std::endl;
}


// 0011000000111001
// 1101010000110001