A,B = map(int,input().split())
bit1 = [0] * 32
bit2 = [0] * 32
for i in range(32):
    if A & (1 << i):
        bit1[i] = 1
for i in range(32):
    if B & (1 << i):
        bit2[i] = 1
cnt = 0
for i in range(31,-1,-1):
    if bit1[i] == 1 and bit2[i] == 0:
        print(0)
        exit()
    if bit1[i] == 0 and bit2[i] == 1:
        cnt += 1
print(pow(2, cnt-1))