A,B = map(int,input().split())
if A==0:
    print(1)
    exit()
if A>B:
    print(0)
    exit()

ans = 1
less = False
for a,b in (zip(bin(A)[2:],bin(B)[2:])):
    if a==b: continue
    if a=='1' and b=='0':
        print(0)
        exit()
    if less:
        ans *= 2
    else:
        less = True
print(ans)