A, B = map(int,input().split())
ans = 1
if A==B:
    print(1)
    exit()
while A or B:
    a = A&1
    b = B&1
    if a == 1 and b == 0:
        ans *= 0
    if a == 0 and b == 1:
        ans *= 2
    A >>= 1
    B >>= 1
print(ans//2)