from sys import stdin


def main():
    input = lambda: stdin.readline()[:-1]
    A, B = map(int, input().split())

    if A & B != A or A | B != B:
        print(0)
        return
    elif A == B:
        print(1)
        return

    i, n = 0, 0
    max_ = max(A, B)
    while max_ > 0:
        ai = A & 1 << i
        bi = B & 1 << i
        if (not ai and bi) or (ai and not bi):
            n += 1
        max_ //= 2
        i += 1
    print(2 ** (n - 1))


main()