# boj, 11050 : 이항 계수 1, python3
import sys
def multiply(arr):
ans = 1
for n in arr:
if n == 0:
return 0
ans *= n
return ans
def list_sort(num):
return sorted(range(1, num + 1), reverse = True)
def binomial_coefficient(n, k):
return multiply(list_sort(n)) // (multiply(list_sort(k)) * multiply(list_sort(n - k)))
N, K = map(int, sys.stdin.readline().split())
print(binomial_coefficient(N, K))