import sys
A,B = list(map(int,input().split()))

count = 0
for i in range(32):
    mask = 1 << i
    if A & mask and B & mask == 0:
        print(0)
        exit()
    if A & mask == 0 and B & mask == 1:
        count += 1
if A == B:
    print(1)
else:
    print(2 ** (count-1))