#include <bits/stdc++.h>
using namespace std;
struct point {
  long long x;
  long long k;
  point(long long a = 0, long long b = 0) {
    x = a;
    k = b;
  }
};
double sqr(double a) { return a * a; }
bool cmp(long long a, long long b) { return a > b; }
int main() {
  long long ans = 0, x, l = 0, s, t = 1, one = 0;
  bool zero = true;
  cin >> s >> x;
  zero = (s == x);
  if (x == 0) {
    if (s % 2 == 1) {
      cout << 0;
    } else {
      cout << 1;
    }
    return 0;
  }
  vector<long long> a(50, 0), b(50, 0);
  vector<long long> sum;
  while (x > 0) {
    a[l] = x % 2;
    if (a[l] == 1) {
      s -= t;
      one++;
    }
    l++;
    t *= 2;
    x /= 2;
  }
  l = 0;
  if (s < 0) {
    cout << 0;
    return 0;
  }
  if (s % 2 == 1) {
    cout << 0 << endl;
    return 0;
  }
  while (s > 0) {
    b[l] = s % 2;
    l++;
    s /= 2;
  }
  for (int i = 50; i > 0; i--) {
    a[i] = a[i - 1];
  }
  a[0] = 0;
  for (int i = 0; i <= 50; i++) {
    if ((b[i] == 1) && (a[i] == 1)) {
      cout << 0;
      return 0;
    }
  }
  long long k = 1;
  for (int i = 0; i < one; i++) k *= 2;
  if (zero) {
    k -= 2;
  }
  cout << k << 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;
struct point {
  long long x;
  long long k;
  point(long long a = 0, long long b = 0) {
    x = a;
    k = b;
  }
};
double sqr(double a) { return a * a; }
bool cmp(long long a, long long b) { return a > b; }
int main() {
  long long ans = 0, x, l = 0, s, t = 1, one = 0;
  bool zero = true;
  cin >> s >> x;
  zero = (s == x);
  if (x == 0) {
    if (s % 2 == 1) {
      cout << 0;
    } else {
      cout << 1;
    }
    return 0;
  }
  vector<long long> a(50, 0), b(50, 0);
  vector<long long> sum;
  while (x > 0) {
    a[l] = x % 2;
    if (a[l] == 1) {
      s -= t;
      one++;
    }
    l++;
    t *= 2;
    x /= 2;
  }
  l = 0;
  if (s < 0) {
    cout << 0;
    return 0;
  }
  if (s % 2 == 1) {
    cout << 0 << endl;
    return 0;
  }
  while (s > 0) {
    b[l] = s % 2;
    l++;
    s /= 2;
  }
  for (int i = 50; i > 0; i--) {
    a[i] = a[i - 1];
  }
  a[0] = 0;
  for (int i = 0; i <= 50; i++) {
    if ((b[i] == 1) && (a[i] == 1)) {
      cout << 0;
      return 0;
    }
  }
  long long k = 1;
  for (int i = 0; i < one; i++) k *= 2;
  if (zero) {
    k -= 2;
  }
  cout << k << endl;
  return 0;
}

```