#include <bits/stdc++.h>
using namespace std;
int main() {
  long long sum, xo;
  long long l = 1;
  cin >> sum >> xo;
  if ((sum - xo) & 1) return cout << "0" << endl, 0;
  long long y = (sum - xo) / 2;
  long long ans = 1;
  bool oo = 1;
  for (int i = 0; i < 64; i++) {
    bool x = (l << i) & xo;
    bool s = (l << i) & sum;
    bool t = (l << i) & y;
    if (t && x) return cout << "0" << endl, 0;
    if ((!x && s) || (!s && x)) oo = 0;
    if (x) ans *= 2;
  }
  if (oo) ans -= 2;
  cout << ans << endl;
  return 0;
}

### Prompt

Your task is to create a Cpp solution to the following problem:

Two positive integers a and b have a sum of s and a bitwise XOR of x. How many possible values are there for the ordered pair (a, b)?

Input

The first line of the input contains two integers s and x (2 ≤ s ≤ 1012, 0 ≤ x ≤ 1012), the sum and bitwise xor of the pair of positive integers, respectively.

Output

Print a single integer, the number of solutions to the given conditions. If no solutions exist, print 0.

Examples

Input

9 5


Output

4


Input

3 3


Output

2


Input

5 2


Output

0

Note

In the first sample, we have the following solutions: (2, 7), (3, 6), (6, 3), (7, 2).

In the second sample, the only solutions are (1, 2) and (2, 1).

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
int main() {
  long long sum, xo;
  long long l = 1;
  cin >> sum >> xo;
  if ((sum - xo) & 1) return cout << "0" << endl, 0;
  long long y = (sum - xo) / 2;
  long long ans = 1;
  bool oo = 1;
  for (int i = 0; i < 64; i++) {
    bool x = (l << i) & xo;
    bool s = (l << i) & sum;
    bool t = (l << i) & y;
    if (t && x) return cout << "0" << endl, 0;
    if ((!x && s) || (!s && x)) oo = 0;
    if (x) ans *= 2;
  }
  if (oo) ans -= 2;
  cout << ans << endl;
  return 0;
}

```