#include <cstdio>
#include <string>
#include <cstdlib>
#include <iostream>
#include <algorithm>
using namespace std;
const int MAXN=30;
typedef long long LL;
LL N,K,Ans=0LL,Num[MAXN];
LL F[MAXN][MAXN];
inline bool check()
{
	LL up=0LL,now=Num[1];
	for(int i=2;i<=N;i++)
	{
		if(Num[i]>now) {now=Num[i];continue;}
		up++;now=Num[i];
	} up++;
	return up==K;
}

int main()
{
	freopen("k.in","r",stdin);
	freopen("k.out","w",stdout);
	cin>>N>>K;
	if(N<=10)
	{
		for(int i=1;i<=N;i++) Num[i]=i;
		if(check()) Ans++;
		while(next_permutation(Num+1,Num+1+N))
			if(check()) Ans++; 
		cout<<Ans<<endl; return 0;
	}
	F[1][1]=1LL;
	for(int i=2;i<=N;i++)
		for(int j=1;j<=K;j++)
			F[i][j]=F[i-1][j]*j+F[i-1][j-1]*(i-(j-1));
	cout<<F[N][K]<<endl;
	return 0;
}