#include <iostream>
#include <string.h>
#include <algorithm>
 
using namespace std;
long long int dp[2][10003];
long long int data[10003];
int main() {
	// your code goes here
	int n,m;
	memset(dp,0,sizeof(dp));
	memset(data,0,sizeof(data));
	cin>>n>>m;
	for(int i=0;i<n;i++){
		cin>>data[i];
	}
	//ずっと頭がぼーっとして何も考えられない
	for(int i=0;i<n;i++){
		dp[1][i]=max(dp[1][i],data[i]);
		for(int j=max(0,i-m+1);j<i;j++){
			dp[0][i+m]=max(dp[0][j+m],dp[1][j]+data[i]);
			dp[1][j+m]=max(dp[1][j+m],dp[1][j]+data[i]);
		}	
		for(int j=0;j<i;j++){
			if(j<i-m+1){
				dp[1][i+1]=max(dp[1][i+1],dp[1][j]+data[i]);
			}
			dp[0][i+m]=max(dp[0][i+m],dp[0][j]+data[i]);
			dp[1][i+1]=max(dp[1][i+1],dp[0][j]+data[i]);
		}
		for(int j=0;j<2;j++){
			dp[j][i+1]=max(dp[j][i+1],dp[j][i]);
		}
 
		for(int j=0;j<13;j++){
			cout<<j<<"("<<dp[0][j]<<" "<<dp[1][j]<<")";
		}
		cout<<endl;
	}
	long long int ans=0;
	for(int i=0;i<2*n+4;i++){
		for(int j=0;j<2;j++){
			ans=max(ans,dp[j][i]);
		}
	}
	cout<<ans<<endl;
	return 0;
}

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