#include<bits/stdc++.h>
using namespace std;
#define mod 1000000007LL
#define ll long long
#define ii pair<int,int>
#define vi vector<int>
int n, a[10005], k;
bool visited[10005][105];
ll dp[10005][1005];
ll foo(int ind, int last)
{
	if(ind == n)
		return 0;
	if(visited[ind][ind-last])
		return dp[ind][ind-last];
	if(ind - last == 2*k+1)
		return (dp[ind][ind-last] = foo(ind+1,ind) + (ll)a[ind]);
	else
		return (dp[ind][ind-last] = min(foo(ind+1,last),foo(ind+1,ind) + (ll)a[ind]));
}
int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(NULL);
	cout.tie(NULL);
	cin >> n >> k;
	set <ii > s;
	for(int i = 0 ;i < n; i++)
		cin >> a[i];

	cout << foo(0,-k-1) << endl;
	return 0;
}