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

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