#include <bits/stdc++.h>
using namespace std;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
using Int = long long;
const char newl = '\n';


template<typename T> void drop(const T &x){cout<<x<<endl;exit(0);}

//INSERT ABOVE HERE
signed main(){
  cin.tie(0);
  ios::sync_with_stdio(0);

  Int a,b;
  cin>>a>>b;
  if((a&b)!=a) drop(0);
  if(a==b) drop(1);

  cout<<(1LL<<(__builtin_popcountll(b-a)-1))<<newl;
  return 0;
}