A, B = map(int, input().split())
x, y = 0, 0
for i in range(60):
    a = (A >> i)&1
    b = (B >> i)&1
    if a == 1 and b == 0:
        x += 1
    if a == 0 and b == 1:
        y += 1
if x:
    print(0)
else:
    print(2 ** (y - 1))