#include <bits/stdc++.h>
using namespace std;
long long s, x;
int main() {
  scanf("%lld %lld", &s, &x);
  long long y = s - x;
  if (y & 1) puts("0"), exit(0);
  if (y < 0) puts("0"), exit(0);
  y >>= 1;
  if (x & y) puts("0"), exit(0);
  s -= 2 * y;
  if (s < 0) puts("0"), exit(0);
  long long ans = 1LL << __builtin_popcountll(s);
  if (!y) ans -= 2;
  printf("%lld\n", max(0LL, ans));
  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 s, x;
int main() {
  scanf("%lld %lld", &s, &x);
  long long y = s - x;
  if (y & 1) puts("0"), exit(0);
  if (y < 0) puts("0"), exit(0);
  y >>= 1;
  if (x & y) puts("0"), exit(0);
  s -= 2 * y;
  if (s < 0) puts("0"), exit(0);
  long long ans = 1LL << __builtin_popcountll(s);
  if (!y) ans -= 2;
  printf("%lld\n", max(0LL, ans));
  return 0;
}

```