#include <bits/stdc++.h>
using namespace std;
void fs(long long &num) {
  num = 0;
  register int c;
  bool sign = false;
  c = getchar();
  if (c == '-') {
    sign = true;
    c = getchar();
  }
  for (; c > 47 && c < 58; c = getchar()) {
    num *= 10;
    num += c - 48;
  }
  if (sign) num *= -1;
}
bool a[140];
int main() {
  long long s, x, co_x, ans = 1;
  fs(s), fs(x);
  if (s < x) {
    cout << "0\n";
    return 0;
  }
  co_x = x;
  vector<int> q;
  while (co_x > 0) {
    q.push_back(co_x % 2);
    co_x /= 2;
  }
  for (int i = 0; i < q.size(); ++i) {
    if (q[i] == 1) {
      ans *= 2;
      a[i] = 1;
    }
  }
  s -= x;
  if (s == 0) {
    ans -= 2;
    cout << ans << '\n';
    return 0;
  }
  q.clear();
  while (s > 0) {
    q.push_back(s % 2);
    s /= 2;
  }
  if (q[0] == 1) {
    cout << "0\n";
    return 0;
  }
  for (int i = 1; i < q.size(); ++i) {
    if (q[i] == 1 && a[i - 1] == 1) ans = 0;
  }
  cout << ans << '\n';
}

### Prompt

Please formulate 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;
void fs(long long &num) {
  num = 0;
  register int c;
  bool sign = false;
  c = getchar();
  if (c == '-') {
    sign = true;
    c = getchar();
  }
  for (; c > 47 && c < 58; c = getchar()) {
    num *= 10;
    num += c - 48;
  }
  if (sign) num *= -1;
}
bool a[140];
int main() {
  long long s, x, co_x, ans = 1;
  fs(s), fs(x);
  if (s < x) {
    cout << "0\n";
    return 0;
  }
  co_x = x;
  vector<int> q;
  while (co_x > 0) {
    q.push_back(co_x % 2);
    co_x /= 2;
  }
  for (int i = 0; i < q.size(); ++i) {
    if (q[i] == 1) {
      ans *= 2;
      a[i] = 1;
    }
  }
  s -= x;
  if (s == 0) {
    ans -= 2;
    cout << ans << '\n';
    return 0;
  }
  q.clear();
  while (s > 0) {
    q.push_back(s % 2);
    s /= 2;
  }
  if (q[0] == 1) {
    cout << "0\n";
    return 0;
  }
  for (int i = 1; i < q.size(); ++i) {
    if (q[i] == 1 && a[i - 1] == 1) ans = 0;
  }
  cout << ans << '\n';
}

```