Pot

#include <bits/stdc++.h>
using namespace std;
int main(){
    int n,m;
    scanf("%d%d",&n,&m);
    int dp[n+1];
    dp[0]=1;
    dp[1]=1;
    for(int i=2;i<=n;i++){
        if(i<=m){
            dp[i]=(2*dp[i-1])%2009;
        }else{
            dp[i]=(2*dp[i-1]-dp[i-m-1])%2009;
        }
        if(dp[i]<0) dp[i]+=2009;
    }
    printf("%d",dp[n]);
}