XOR Equation

Description:

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.

Sample Input:

9 5

Sample Output:

4

Sample Input:

3 3

Sample Output:

2

Sample Input:

5 2

Sample 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).