import math
N, S = map(int, input().split())
a = []
num = list(range(S))
for i in range(S):
    id = N // math.factorial(S - 1 - i)
    N %= math.factorial(S - 1 - i)
    a.append(num.pop(id))

b = [-1] * S

for i in range(S):
    b[a[i]] = i

num = list(range(S))

ans = 0
for i in range(S):
    ans += math.factorial(S - 1 - i) * num.pop(num.index(b[i]))
print(ans)