#include <bits/stdc++.h>
using namespace std;
long long solve(long long s, long long x) {
  if ((s - x) % 2 || x > s) {
    return 0;
  }
  vector<int> sb(64, 0), xb(64, 0), sxb(64, 0);
  long long t = s, k = 0;
  while (t > 0) {
    sb[k] = t % 2;
    t /= 2;
    k++;
  }
  t = x;
  k = 0;
  while (t > 0) {
    xb[k] = t % 2;
    t /= 2;
    k++;
  }
  t = (s - x) / 2;
  k = 0;
  while (t > 0) {
    sxb[k] = t % 2;
    t /= 2;
    k++;
  }
  long long wyn = 0;
  for (int i = 0; i < 64; i++) {
    wyn += xb[i];
  }
  wyn = pow(2, wyn);
  if (s == x) wyn -= 2;
  bool spr = 1;
  for (int i = 0; i < 64; i++)
    if (sxb[i] + xb[i] == 2) spr = 0;
  if (spr) return wyn;
  ;
  return 0;
}
long long brut(long long s, long long x) {
  long long wyn = 0;
  for (int i = 1; i < s; i++) {
    if ((i ^ (s - i)) == x) wyn++;
  }
  return wyn;
}
int main() {
  ios_base::sync_with_stdio(0);
  long long s, x;
  cin >> s >> x;
  cout << solve(s, x);
  return 0;
}
