#include <iostream>
#include <string.h>
#include <algorithm>
using namespace std;
 
 
 
int main() {
	// your code goes here
	int n,m;
	long long int data[10003];
	long long int dp[2][10003];
	memset(data,0,sizeof(data));
	memset(dp,0,sizeof(dp));
	cin>>n>>m;
	for(int i=0;i<n;i++){
		cin>>data[i];
	}
	for(int i=0;i<n;i++){
		dp[1][i]=max(dp[1][i],data[i]);
		for(int j=0;j<i;j++){
			long long int d=data[i]+dp[1][j];
			long long int d2=data[i]+dp[0][j];
			if(j<=i-m+1){
				dp[1][i+1]=max(dp[1][i+1],d);
			}else if(i<=j+m){
				dp[1][j+m-1]=max(dp[1][j+m-1],d);
			}
 
 
			dp[1][i+1]=max(dp[1][i+1],d2);
			dp[0][i+m-1]=max(dp[0][i+m-1],d2);
		}
		dp[1][i+1]=max(dp[1][i+1],dp[1][i]);
		dp[0][i+1]=max(dp[0][i+1],dp[0][i]);
	}
	long long int ans=0;
	for(int i=0;i<n*2+3;i++){
		ans=max(ans,dp[0][i]);
		ans=max(ans,dp[1][i]);
	}
	cout<<ans<<endl;
	return 0;
}

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