a,b = map(int,input().split())
cnt = 0
while a > 0 or b > 0:
    c,d = a&1, b&1
    if c != d:
        if d:
            cnt += 1
        else:
            print(0)
            exit()
    a //= 2
    b //= 2
if cnt == 0:
    print(1)
else:
    print(2 ** (cnt - 1))