import sys

if len(sys.argv) == 2:
    sys.stdin = open(sys.argv[1])

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

A = [0 for _ in range(32)]
B = [0 for _ in range(32)]
for i in range(32):
    a, r = divmod(a, 2)
    A[i] = r
    b, r = divmod(b, 2)
    B[i] = r

flag = True
d = 0
for i in range(32):
    if A[i] == 1:
        if A[i] != B[i]:
            flag = False
            break
    else:
        if B[i] == 1:
            d += 1
if flag:
    if d == 0:
        print(1)
    else:
        print(pow(2, d - 1))
else:
    print(0)