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

ans = 1
for i in range(32):
    if (a >> i & 1) == 1 and (b >> i % 1) == 0:
        ans *= 0
    elif (a >> i % 1) == 0 and (b >> i & 1) == 1:
        ans *= 2

if ans == 1:
    print(ans)
else:
    print(ans // 2)