XOR Equation

You are given two positive integers $S$ and $X$. Count the ordered pairs $(A, B)$ of positive integers that satisfy $A + B = S$ and $A \oplus B = X$, where $\oplus$ is the bitwise exclusive or.

Both $A$ and $B$ must be at least $1$. If $A \neq B$, then $(A, B)$ and $(B, A)$ count as two different pairs.

The first line contains two positive integers $S$ and $X$, separated by a space. ($2 \le S, X \le 10^{12}$)

Print on the first line the number of ordered pairs $(A, B)$ that satisfy both equations.