a, b = map(int, input().split())

ans = 0
for i in range(32):
    if (a >> i & 1) and not (b >> i & 1):
        print(0)
        exit()
    if not (a >> i & 1) and (b >> i & 1):
        ans += 1
if ans == 0:
    print(1)
else:
    print(2**ans // 2)