#include <fstream>
#include <algorithm>
#define N 110
#define M 110
using namespace std;
typedef long long ll;
ifstream in("nucle.in");
ofstream out("nucle.out");
int n,m;
ll F[N][M]={0};
//表示决策到第i个，已经连续放了j个
void read()
{
	in>>n>>m;
}
void work()
{
	int i,j;
	ll ans=0;
	//for(i=1;i<=n;i++)F[i][0]=F[i][1]=1;
	F[1][0]=F[1][1]=1;
	for(i=2;i<=n;i++)
	{
		for(j=0;j<m;j++)F[i][0]+=F[i-1][j];
		for(j=0;j<m;j++)F[i][j]+=F[i-1][j-1];
	}
	for(j=0;j<m;j++)ans+=F[n][j];
	out<<ans<<endl;
}
int main()
{
	read();
	work();
	return 0;
}