#include <bits/stdc++.h>
using namespace std;
char _;
const long long maxN = 200 * 1000 + 5;
const long long maxM = 5000 + 5;
const long long mod = 1000 * 1000 * 1000 + 7;
const long long base = 701;
const long long SQ = 500;
const long long maxL = 20;
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  long long s, x;
  cin >> s >> x;
  if (s < x) {
    cout << 0 << endl;
    return 0;
  }
  long long ans = 1;
  for (long long i = 0; i < 40; i++)
    if (x >> i & 1) ans *= 2;
  long long carry = 0;
  for (long long i = 40; i >= 0; i--) {
    long long g = (s >> i & 1), f = (x >> i & 1);
    if (carry == 0 && f == 0 && g == 0) continue;
    if (carry == 0 && f == 0 && g == 1) {
      carry = 1;
      continue;
    }
    if (carry == 0 && f == 1 && g == 0) {
      cout << 0 << endl;
      return 0;
    }
    if (carry == 0 && f == 1 && g == 1) continue;
    if (carry == 1 && f == 0 && g == 0) {
      carry = 0;
      continue;
    }
    if (carry == 1 && f == 0 && g == 1) continue;
    if (carry == 1 && f == 1 && g == 0) continue;
    if (carry == 1 && f == 1 && g == 1) {
      cout << 0 << endl;
      return 0;
    }
  }
  if (s == x) ans -= 2;
  if (carry)
    cout << 0 << endl;
  else
    cout << ans << endl;
  return 0;
}
