找到规律,就是排列组合,找不到规律就难了
#画了一下图找到规律就是pCr种走法,跟排列组合是一样的Cpr
from math import factorial as fact
while 1:
try:
n,m = [int(x) for x in input().strip().split()]
p =n+m
r =n
N = fact(p) // (fact(p-r)*fact(r))
print(N)
except:
break