#include <iostream>
using namespace std;
struct numarmare
{
    unsigned char C[501];
    int n;
};
numarmare A[501][501];

void aduna(numarmare A, numarmare B, numarmare &S)//s=a+b
{   int i,t,c,p;
	if(A.n<B.n)
		{ p=B.n;//nr max de cifre
	      for(i=A.n+1;i<=B.n;i++) A.C[i]=0;//completez cu 0
		}
	else { p=A.n;//nr max de cifre
	       for(i=B.n+1;i<=A.n;i++) B.C[i]=0;//completez cu 0
 	     }
	t=0;
	for(i=1;i<=p;i++)
	{
		c=A.C[i]+B.C[i]+t; //adun cifra cu cifra
		S.C[i]=c%10;//restul se pune
		t=c/10;//catul e transport
	}
	if(t==1)// a ramas transport
	{
		p++;//avem cu o cifra mai mult
		S.C[p]=t;
	}
	S.n=p;
}

void afisare(numarmare A)
{
    for(int i=A.n;i>=1;i--)
        cout<<(int)A.C[i];
}

int main()
{
    int k,n;
    cin>>n>>k;
    A[0][0].n=1;
    A[0][0].C[1]=1;
    for(int i=1;i<=n;i++)
        for(int j=0;j<=i;j++)
            if(j==0) { A[i][j].n=1; A[i][j].C[1]=1;}
            else aduna(A[i-1][j-1],A[i-1][j],A[i][j]);
    afisare(A[n][k]);
    return 0;
}