//g++ -std=c++0x your_file.cpp -o your_program
#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>
#include <math.h>
#include <vector>
#include <cstring>
#include <queue>
#include <cstdio>
#include <cstdlib>
#include <map>
#include <set>
#define fname ""
#define mp make_pair
#define F first
#define pb push_back
#define S second
#define ub upper_bound
#define lb lower_bound
#define inf 2000000000
#define INF 2000000000000000000ll
using namespace std;

const int maxn = 10101;

long long d[maxn], previ[maxn];

int a[maxn];

int main()
{
	int n, k;
	cin >> n >> k;
	for (int i = 1; i <= n; i++)
		scanf("%d", &a[i]);
	int pos;
	for (int i = 1; i <= n; i++)
	{
		d[i] = previ[i] = inf;
		for (int j = 1; j <= k + 1 && i - j >= 0; j++)
			d[i] = min(d[i], a[i] + previ[i - j]);
		for (int j = 0; j <= k && i - j >= 1; j++)
			previ[i] = min(previ[i], d[i - j]);
//		cout << d[i] << " " << previ[i] << endl;
	}
	cout << previ[n];
	return 0;
}