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

if a == b:
    print(1)
    exit()

if a > b:
    print(0)
    exit()

ans = 1
a = list(format(a, 'b'))
b = list(format(b, 'b'))
a.reverse()
b.reverse()

if len(b) < len(a):
    b = b+['0']*(len(a)-len(b))
else:
    a = a+['0']*(len(b)-len(a))

for i, j in zip(a, b):
    if i == '0' and j == '1':
        ans *= 2
    elif i == '0' and j == '0':
        ans *= 1
    elif i == '1' and j == '1':
        ans *= 1
    else:
        ans = 0

print(ans//2)