#include <bits/stdc++.h>
using namespace std;
long long S, X, ans, sum;
void rip() {
  puts("0");
  exit(0);
}
int main() {
  scanf("%lld %lld", &S, &X);
  sum = X;
  for (long long i = 60; i--;)
    if (((1LL << i) & X) == 0) {
      if (sum + (1LL << (i + 1)) <= S) sum += (1LL << (i + 1));
    }
  if (sum != S) rip();
  long long n = (long long)__builtin_popcountll(X);
  ans = (1LL << n);
  if (sum == X) ans -= 2;
  printf("%lld\n", ans);
  return 0;
}

### Prompt

Construct a CPP code solution to the problem outlined:

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, ans, sum;
void rip() {
  puts("0");
  exit(0);
}
int main() {
  scanf("%lld %lld", &S, &X);
  sum = X;
  for (long long i = 60; i--;)
    if (((1LL << i) & X) == 0) {
      if (sum + (1LL << (i + 1)) <= S) sum += (1LL << (i + 1));
    }
  if (sum != S) rip();
  long long n = (long long)__builtin_popcountll(X);
  ans = (1LL << n);
  if (sum == X) ans -= 2;
  printf("%lld\n", ans);
  return 0;
}

```