#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int s, x;
  cin >> s >> x;
  long long int tand = (s - x);
  long long int And = tand / 2;
  if (s < x or tand % 2 or (x & And)) {
    cout << 0 << endl;
    return 0;
  }
  long long int c = 0;
  while (x) {
    if (x & 1) c++;
    x >>= 1;
  }
  if (And == 0) {
    cout << ((long long int)1 << c) - 2 << endl;
  } else
    cout << ((long long int)1 << c) << 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 int s, x;
  cin >> s >> x;
  long long int tand = (s - x);
  long long int And = tand / 2;
  if (s < x or tand % 2 or (x & And)) {
    cout << 0 << endl;
    return 0;
  }
  long long int c = 0;
  while (x) {
    if (x & 1) c++;
    x >>= 1;
  }
  if (And == 0) {
    cout << ((long long int)1 << c) - 2 << endl;
  } else
    cout << ((long long int)1 << c) << endl;
  ;
  return 0;
}

```