#include <iostream>
#include <random>
#include <bits/stdc++.h>
using namespace std;
using ull = __int128;
using ll = long long;

int main(){
    ll a,b;
    cin>>a>>b;
      bitset<40> n(a);
      bitset<40> m(b);
      ll ans=1;
      for(int i=0;i<40;i++){
          if(n.test(i)==1&&m.test(i)==0){
              ans=0;
          }
          if(n.test(i)==0&&m.test(i)==1){
              ans=ans+ans;
          }
          }
          ans=ans/2;
          if(a==b){
              ans++;
          }
          cout<<ans<<endl;
      }