#include <bits/stdc++.h>
using namespace std;
inline long long getint() {
  long long _x = 0, _tmp = 1;
  char _tc = getchar();
  while ((_tc < '0' || _tc > '9') && _tc != '-') _tc = getchar();
  if (_tc == '-') _tc = getchar(), _tmp = -1;
  while (_tc >= '0' && _tc <= '9') _x *= 10, _x += (_tc - '0'), _tc = getchar();
  return _x * _tmp;
}
long long mypow(long long _a, long long _x, long long _mod) {
  if (_x == 0) return 1ll;
  long long _tmp = mypow(_a, _x / 2, _mod);
  _tmp = (_tmp * _tmp) % _mod;
  if (_x & 1) _tmp = (_tmp * _a) % _mod;
  return _tmp;
}
inline long long add(long long _x, long long _y,
                     long long _mod = 1000000007ll) {
  long long _ = _x + _y;
  if (_ >= _mod) _ -= _mod;
  return _;
}
inline long long sub(long long _x, long long _y,
                     long long _mod = 1000000007ll) {
  long long _ = _x - _y;
  if (_ < 0) _ += _mod;
  return _;
}
inline long long mul(long long _x, long long _y,
                     long long _mod = 1000000007ll) {
  long long _ = _x * _y;
  if (_ >= _mod) _ %= _mod;
  return _;
}
inline bool equal(double _x, double _y) {
  return _x > _y - 1e-9 && _x < _y + 1e-9;
}
int __ = 1, _cs;
void build() {}
long long s, x;
void init() {
  s = getint();
  x = getint();
}
void solve() {
  long long ans = 1, ps = 0;
  for (int bt = 50; bt >= 0; bt--)
    if ((x >> bt) & 1ll) {
      ans <<= 1;
      ps += (1ll << bt);
    }
  bool flag = false;
  for (int bt = 50; bt >= 0; bt--)
    if (((x >> bt) & 1ll) == 0ll) {
      if (ps + (1ll << (bt + 1)) <= s) {
        ps += (1ll << (bt + 1));
        flag = true;
      }
    }
  if (!flag) ans -= 2;
  if (ps != s)
    puts("0");
  else
    cout << max(ans, 0ll) << endl;
}
int main() {
  build();
  while (__--) {
    init();
    solve();
  }
}
