def pyon(n0, d0):
    count = 0
    c = n0 // d0
    m = n0 % d0
    for _ in range(n0):
        if n0 == d0: return count
        else:
            if m == 0: count += c - 1
            else: count += c
            if m >= 1:
                count *= d0
            n0 = d0


n, d = list(map(int, input().split()))
p = pyon(n, d)
print(p)