n, m = map(int, input().split())

assert 1 <= n <= 10 ** 9
assert 1 <= m <= 10 ** 9

if n % 2 == 0:
    print(n * m)
else:
    h = n // 2
    flag = 0
    ans = 0
    for i in reversed(range(30)):
        if m >> i & 1:
            ans += n-1 << i
            flag += 1
        else:
            ans += (flag//2) * 2 << i
    print(ans)