#include <bits/stdc++.h>
using namespace std;
const long double eps = 1e-9;
const long double pi = acos(-1.0);
const long long inf = 1e+9;
#pragma comment(linker, "/STACK:36777216")
template <typename T>
istream &operator>>(istream &, vector<T> &);
template <typename T>
ostream &operator<<(ostream &, const vector<T> &);
long long s, x;
int bit(long long x, int pos) { return (x & (1LL << pos)) > 0; }
void solve() {
  cin >> s >> x;
  int l = 45;
  while (bit(s, l) == 0) l--;
  vector<vector<long long> > dp(l + 2, vector<long long>(2, 0));
  dp[0][0] = 1;
  for (int i = 1; i <= l + 1; i++) {
    int bs = bit(s, i - 1);
    int bx = bit(x, i - 1);
    if (bs == 0) {
      if (bx == 0) {
        dp[i][0] = dp[i - 1][0];
        dp[i][1] = dp[i - 1][0];
      } else {
        dp[i][1] += 2 * dp[i - 1][1];
      }
    } else {
      if (bx == 0) {
        dp[i][0] = dp[i - 1][1];
        dp[i][1] = dp[i - 1][1];
      } else {
        dp[i][0] += 2 * dp[i - 1][0];
      }
    }
  }
  long long ans = dp[l + 1][0];
  if (x > s) ans = 0;
  if (x == 0) {
    if (s % 2 == 0)
      ans = 1;
    else
      ans = 0;
  }
  if (x == s) ans -= 2;
  cout << ans << endl;
}
int main() {
  solve();
  return 0;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &v) {
  for (int i = 0; i < v.size(); ++i) is >> v[i];
  return is;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  for (int i = 0; i < v.size(); ++i) os << v[i];
  return os;
}
