#include <bits/stdc++.h>
using namespace std;
long long x, s, i, la, lb, ans, cnt;
bool a[1005], b[1005];
int main() {
  cin >> x >> s;
  if (x < s) {
    cout << 0;
    return 0;
  }
  i = s;
  while (i > 0) {
    a[la++] = i % 2;
    i /= 2;
  }
  i = x - s;
  while (i > 0) {
    b[lb++] = i % 2;
    i /= 2;
  }
  if (b[0] == 1) {
    cout << 0;
    return 0;
  }
  for (i = 1; i < lb; i++) {
    if (b[i] == 1 && a[i - 1] == 1) {
      cout << 0;
      return 0;
    }
    if (b[i] == 1) cnt++;
  }
  ans = 1;
  for (i = 0; i < la; i++) {
    if (a[i] == 1) ans *= 2;
  }
  if (cnt == 0) ans -= 2;
  cout << ans << endl;
  return 0;
}

### Prompt

Develop a solution in Cpp to the problem described below:

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;
long long x, s, i, la, lb, ans, cnt;
bool a[1005], b[1005];
int main() {
  cin >> x >> s;
  if (x < s) {
    cout << 0;
    return 0;
  }
  i = s;
  while (i > 0) {
    a[la++] = i % 2;
    i /= 2;
  }
  i = x - s;
  while (i > 0) {
    b[lb++] = i % 2;
    i /= 2;
  }
  if (b[0] == 1) {
    cout << 0;
    return 0;
  }
  for (i = 1; i < lb; i++) {
    if (b[i] == 1 && a[i - 1] == 1) {
      cout << 0;
      return 0;
    }
    if (b[i] == 1) cnt++;
  }
  ans = 1;
  for (i = 0; i < la; i++) {
    if (a[i] == 1) ans *= 2;
  }
  if (cnt == 0) ans -= 2;
  cout << ans << endl;
  return 0;
}

```