A,B = map(int,input().split())
if A>B:
    print(0)
    exit()

ans = 1
less = False
for i in range(32,-1,-1):
    a = (A>>i)&1
    b = (B>>i)&1
    if a==b: continue
    if a==1 and b==0:
        print(0)
        exit()
    if less:
        ans *= 2
    else:
        less = True
print(ans)