#include<cstdio>
#include<iostream>
using namespace std;
typedef long long int ll;
ll n,m;
ll func(ll x,ll y)
{
    if(x<0||x<y) return 0;
    if(x==y) return 1;
    return func(x-1,y-1)+func(x-1,y);
}
ll jc(ll x)
{
    if(x<=1) return 1;
    return x*jc(x-1);
}
int main()
{
    scanf("%lld%lld",&n,&m);
    

    printf("%lld",func(n,m)*jc(m));
    getchar();getchar();
    return 0;

}