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

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