#include <iostream>
#include <string.h>
#include <algorithm>
using namespace std;
long long int dp[2][10001];
long long int xs[10001];
int main() {
	memset(dp,0,sizeof(dp));
	memset(xs,0,sizeof(xs));
	int n,k;
	cin>>n>>k;
	for(int i=0;i<n;i++){
		cin>>xs[i];
 
	}
	for(int i=0;i<n;i++){
		for(int j=i;j<n;j++){
			dp[1][j+1]=max(dp[1][j+1],dp[0][i]+xs[j]);
			dp[0][j+k]=max(dp[0][j+k],dp[0][i]+xs[j]);
		}
		for(int j=i;j<n;j++){
			if(j<i+k){
				if(i==1)cout<<"("<<i<<" "<<j<<" "<<k<<")";
				dp[1][i+k]=max(dp[1][i+k],dp[1][i]+xs[j]);
				dp[0][j+k]=max(dp[0][j+k],dp[1][i]+xs[j]);
			}else{
				if(i==1)cout<<"("<<i<<" "<<j<<")";
				dp[1][j+1]=max(dp[1][j+1],dp[1][i]+xs[j]);
				dp[0][i+k]=max(dp[0][i+k],dp[1][i]+xs[j]);
				dp[0][i+k]=max(dp[0][i+k],dp[1][i]);
			}
		}
	}
	long long int ans=0;
	for(int i=0;i<10000;i++){
		if(ans<dp[0][i])ans=dp[0][i];
		if(ans<dp[1][i])ans=dp[1][i];
		//cout<<"("<<i<<","<<dp[0][i]<<","<<dp[1][i]<<")";
	}
	cout<<ans<<endl;
	return 0;
}

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