#include <iostream>
using namspace std;
int f(int n)
{
    int mul=1;
    for(int i=3;i<=;i++)
        mul*=i;
    return mul;
}
int main()
{
    int n,m;
    while(cin >> n >> m)
    {
        cout << f(n)/(f(n)*f(n-m)) << endl;
    }
    return 0;
}
hfqe;orghepoghehpehg[h[hbhbpobhpohbpoehpo2
htooooooooooooooooooooooooooooooooooooopoooooooooooooooooooooooooooooooooooooooooooooooooooooogjerogheophp'bhpobhpobhopbhopbjbjmr[pbr[pbwbrb
br
bjrrtbjtpbjrtb[pjtnptbjptjbptjbptjbpbjpbjpb[rjb[rptjnpb'ptjk]54jh]rek]khg]erkh4]bk4]h]54hj]nmj45]j]4jn]
/
/
/
/
/
/
/

l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
l
k
k
k
gbk
gbkg
kg
k
k
k
hk
thk
thkt
k
kj
ku
jyl
gly
;6
fvl
hlt
h
rk
rkh
tku
6y
4grhk5y5l
ghk
5k5
hk
rk
k5
k