import java.io.*;
import java.util.*;

public class Solution {
    
    static Map<Integer, Map<Integer, Long>> map = new HashMap<>();
    
    static long cost(long[] c, int n, int k, int start, int end) {
        
        if (map.containsKey(start)) {
            if (map.get(start).containsKey(end)) {
                return map.get(start).get(end);
            }
        } else {
            map.put(start, new HashMap<Integer, Long>());
        }
        
        long cost = Long.MAX_VALUE;
        if (end - start <= k) {
            for (int i = start; i <= end; i++) {
                cost = Math.min(cost, c[i]);
            }
        } else {
        
        
        for (int i = Math.max(0, start - k); i <= Math.min(n-1, end + k - 1); i++) {
            //System.out.println(start + " " + end + " " + (end - start));
            long nc = c[i];
            if (i - k > start) {
                //System.out.println(i + " " + "start");
                nc += cost(c, n, k, start, i - k);
            }
            if (i + k < end) {
                //System.out.println(i + " " + "end");
                nc += cost(c, n, k, i + k + 1, end);
            }
            cost = Math.min(cost, nc);
        }
        }
        map.get(start).put(end, cost);
        return cost;
    }

    public static void main(String[] args) {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        long[] c = new long[n];
        for (int i = 0; i < n; i++) {
            c[i] = sc.nextLong();
        }
        
        System.out.println(cost(c, n, k, 0, n-1));
    }
}