#include<iostream>
using namespace std;
int main(){
    long long n,m,f[52][6]={0};
    cin>>n>>m;
    f[0][0]=1;
    f[1][0]=1;
    for(int i=1;i<=n;i++){
        //cout<<f[i][0]<<" ";
        f[i+1][0]=f[i][0];
        for(int j=1;j<=m-1;j++){
            f[i][j]=f[i-1][j-1];
            f[i+1][0]+=f[i][j];
            if(j==i) break;
            //cout<<f[i][j]<<" ";
        }
        //cout<<endl;
    }
    cout<<f[n+1][0];
}