#include<iostream>

using namespace std;

signed main(){
  long long A, B;
  long long ans = 1, con = 0;
  
  cin>>A>>B;

  if((A|B) != A && (A|B) != B){
    cout<<0<<endl;
    return 0;
  }

  A ^= B;
  
  while(A){
    if(A&1) con++;
    A >>= 1;
  }

  if(con) ans <<= con-1;

  cout<<ans<<endl;
  
  
  return 0;
}