#include<bits/stdc++.h>
#define boost ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
#define pb push_back
#define mp make_pair
#define ll long long int
#define M 1000000007
#define PI 3.14159265
using namespace std;
int main()
{
	int n,k;
	cin>>n>>k;
	int a[n];
	bool b[n];
	int track[n];
	for(int i=0;i<n;i++)
	{
		cin>>a[i];
		track[i]=a[i];
		b[i]=1;
	}
	
	sort(track,track+n);
	ll ans=0;
	for(int i=0;i<n;i++)
	{
		int z=track[i];
		ans+=z;
		for(int j=0;j<n;j++)
		{
			if((a[j]==z)&&(b[j]!=0))
			{
				int p=k,start=j-1,end=j+1;
				while((p--)&&(end<n)&&(start>=0))
				{
					b[start]=0;
					start--;
					b[end]=0;
					end++;
				}
			}
		}
		bool flag=0;
			for(int q=0;q<n;q++)
			{
				if(b[q]==1)
				{
					flag=1;
					break;
				}
			}
			
			if(flag==0)
			break;
	}
	
	cout<<ans;
	
	
	return 0;
}