def main():
    n, m = map(int, input().split())
    if n == 1: return 0
    if not n % 2: return m * n
    ans = m * (n - 1)
    f = 0
    for i in range(30, -1, -1):
        if not f:
            if m >> i & 1:
                f = 1
        else:
            if m >> i & 1:
                f += 1
            else:
                ans +=  (1 << i) * (f // 2) * 2
    return ans

print(main())