#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define FOR(i,b,e) for (int i=(int)(b); i<(int)(e); i++)
#define ALL(x) (x).begin(), (x).end()

const double PI = acos(-1);

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  long long a, b;
  cin >> a >> b;

  if (a == b)
    cout << 1 << endl;
  else {
    int c = 0;
    bool ck = true;
    REP (i, 50) {
      if (a & 1LL << i) {
        if (!(b & 1LL << i))
          ck = false;
      } else {
        if (b & 1LL << i)
          ++c;
      }
    }

    if (!ck)
      cout << 0 << endl;
    else
      cout << (1LL<<(c-1)) << endl;
  }
  return 0;
}