#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef long long ll;
typedef pair<int,int> P;

int main(){
  ll a, b;
  cin >> a >> b;
  if (a == b) {
    cout << 1 << endl;
    return 0;
  }
  ll res = 1;
  for (int i = 0; i < 32; i++) {
    int bit1 = (a & (1 << i)), bit2 = (b & (1 << i));
    if (bit1 && !bit2) {
      cout << 0 << endl;
      return 0;
    }
    if (!bit1 && bit2) res *= 2; 
  }
  cout << res / 2 << endl;
  return 0;
}