#include <bits/stdc++.h>
using namespace std;
long long int i, j, k, m, n, v[200001], w[200001];
int main() {
  ios::sync_with_stdio(false);
  cout.precision(10);
  cout << fixed;
  long long int s, first;
  cin >> s >> first;
  long long int rasp = 0;
  if (s == first) rasp -= 2;
  s -= first;
  if (s < 0 || s % 2 == 1) {
    cout << 0;
    return 0;
  }
  for (i = 1; i <= 60; ++i)
    if (s & (1ll << i) && (first & (1ll << (i - 1ll)))) {
      cout << 0;
      return 0;
    }
  cout << (1ll << (__builtin_popcountll(first))) + rasp;
  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;
long long int i, j, k, m, n, v[200001], w[200001];
int main() {
  ios::sync_with_stdio(false);
  cout.precision(10);
  cout << fixed;
  long long int s, first;
  cin >> s >> first;
  long long int rasp = 0;
  if (s == first) rasp -= 2;
  s -= first;
  if (s < 0 || s % 2 == 1) {
    cout << 0;
    return 0;
  }
  for (i = 1; i <= 60; ++i)
    if (s & (1ll << i) && (first & (1ll << (i - 1ll)))) {
      cout << 0;
      return 0;
    }
  cout << (1ll << (__builtin_popcountll(first))) + rasp;
  return 0;
}

```