#include <iostream>
using namespace std;
int main(void){
    int A,B;
    cin >> A >> B;
    if((A&B)==A){
        B-=A;
        int p=1;
        for(int i=0;i<31;i++){
            if(B & (1<<i))p*=2;
        }
        cout << (p+1)/2 <<endl;
    }else cout << 0 << endl; 
    return 0;
}