#27917: Python
11030067@mail.hpsh.tp.edu.tw
(和平110級鄧雨珊)
def q(n):
ans=1
for i in range(1, n+1):
ans*=i
return ans
import sys
for g in sys.stdin:
n, m=map(int, g.split())
print(q(n)//(q(m)*q(n-m)))