A, B = map(int,input().split())
if(A == B):
    print(1)
    exit()
res = 1
for i in range(33):
    if((A>>i)&1 and not((B>>i)&1)):
        print(0)
        exit(0)
    if(not((A>>i)&1)  and (B>>i)&1):
        res *= 2

res //= 2
print(res)