#include <bits/stdc++.h>
using namespace std;
char _;
const long long maxN = 200 * 1000 + 5;
const long long maxM = 5000 + 5;
const long long mod = 1000 * 1000 * 1000 + 7;
const long long base = 701;
const long long SQ = 500;
const long long maxL = 20;
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  long long s, x;
  cin >> s >> x;
  if (s < x) {
    cout << 0 << endl;
    return 0;
  }
  long long ans = 1;
  for (long long i = 0; i < 40; i++)
    if (x >> i & 1) ans *= 2;
  long long carry = 0;
  for (long long i = 40; i >= 0; i--) {
    long long g = (s >> i & 1), f = (x >> i & 1);
    if (carry == 0 && f == 0 && g == 0) continue;
    if (carry == 0 && f == 0 && g == 1) {
      carry = 1;
      continue;
    }
    if (carry == 0 && f == 1 && g == 0) {
      cout << 0 << endl;
      return 0;
    }
    if (carry == 0 && f == 1 && g == 1) continue;
    if (carry == 1 && f == 0 && g == 0) {
      carry = 0;
      continue;
    }
    if (carry == 1 && f == 0 && g == 1) continue;
    if (carry == 1 && f == 1 && g == 0) continue;
    if (carry == 1 && f == 1 && g == 1) {
      cout << 0 << endl;
      return 0;
    }
  }
  if (s == x) ans -= 2;
  if (carry)
    cout << 0 << endl;
  else
    cout << ans << 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;
char _;
const long long maxN = 200 * 1000 + 5;
const long long maxM = 5000 + 5;
const long long mod = 1000 * 1000 * 1000 + 7;
const long long base = 701;
const long long SQ = 500;
const long long maxL = 20;
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  long long s, x;
  cin >> s >> x;
  if (s < x) {
    cout << 0 << endl;
    return 0;
  }
  long long ans = 1;
  for (long long i = 0; i < 40; i++)
    if (x >> i & 1) ans *= 2;
  long long carry = 0;
  for (long long i = 40; i >= 0; i--) {
    long long g = (s >> i & 1), f = (x >> i & 1);
    if (carry == 0 && f == 0 && g == 0) continue;
    if (carry == 0 && f == 0 && g == 1) {
      carry = 1;
      continue;
    }
    if (carry == 0 && f == 1 && g == 0) {
      cout << 0 << endl;
      return 0;
    }
    if (carry == 0 && f == 1 && g == 1) continue;
    if (carry == 1 && f == 0 && g == 0) {
      carry = 0;
      continue;
    }
    if (carry == 1 && f == 0 && g == 1) continue;
    if (carry == 1 && f == 1 && g == 0) continue;
    if (carry == 1 && f == 1 && g == 1) {
      cout << 0 << endl;
      return 0;
    }
  }
  if (s == x) ans -= 2;
  if (carry)
    cout << 0 << endl;
  else
    cout << ans << endl;
  return 0;
}

```