#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n,k;
    cin>>n>>k;
    int ar[n];
    for(int x=0;x<n;x++){
        cin>>ar[x];}
    int flag=0;int sum=0;
    int id=0;
    while(flag==0){
    int psm=0;
    for(int x=0+k;x<=n-k;x++)
        {int s1=0,s2=0;
        for(int y1=1;y1<=k;y1++){
            s1=s1+ar[x-y1];}
        for(int y1=1;y1<=k;y1++){
            s2=s2+ar[x+y1];}
        int jk=s1+s2;
        if(jk>psm){
            psm=jk;
            id=x;
        }
        
    }
    for(int u1=id-1;u1>=0;u1--)
        {
        ar[u1]=0;
    }
     for(int u1=id+1;u1<n;u1++)
        {
        ar[u1]=0;
    }
        
    sum=sum+ar[id];
        int st=1;
        ar[id]=0;
    for(int b=0;b<n;b++)
        {
        if(ar[b]!=0){
            st=0;
        }
    }    if(st==1){flag=1;}
    }
    cout<<sum;
    return 0;
}