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)?

The first line of the input contains two integers s and x (2 \le s \le 1012, 0 \le x \le 1012), the sum and bitwise xor of the pair of positive integers, respectively.

Print a single integer, the number of solutions to the given conditions. If no solutions exist, print 0.

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).