N, S = map(int, input().split())
factorial = [1]
for i in range(1, S + 1):
    factorial.append(factorial[-1] * i)


def f(x):
    """x番目の順列が何か求める。O(S^2)"""
    cur = x
    numbers = list(range(1, S + 1))
    res = []
    for i in range(1, S + 1):
        d, cur = divmod(cur, factorial[S - i])
        res.append(numbers[d])
        numbers.pop(d)
    return res


perm = f(N)
inv_perm = [0] * S
for i, x in enumerate(perm, 1):
    inv_perm[x - 1] = i

# bisect
l, r = -1, factorial[S]
while r - l > 1:
    m = (r + l) // 2
    if f(m) < inv_perm:
        l = m
    else:
        r = m
print(r)