There are N stones, numbered 1, 2, \ldots, N. For each i (1 \leq i \leq N), the height of Stone i is h_i.

There is a frog who is initially on Stone 1. He will repeat the following action some number of times to reach Stone N:

* If the frog is currently on Stone i, jump to one of the following: Stone i + 1, i + 2, \ldots, i + K. Here, a cost of |h_i - h_j| is incurred, where j is the stone to land on.



Find the minimum possible total cost incurred before the frog reaches Stone N.

Constraints

* All values in input are integers.
* 2 \leq N \leq 10^5
* 1 \leq K \leq 100
* 1 \leq h_i \leq 10^4

Input

Input is given from Standard Input in the following format:


N K
h_1 h_2 \ldots h_N


Output

Print the minimum possible total cost incurred.

Examples

Input

5 3
10 30 40 50 20


Output

30


Input

3 1
10 20 10


Output

20


Input

2 100
10 10


Output

0


Input

10 4
40 10 20 70 80 10 20 70 80 60


Output

40
import java.util.*;
import java.io.*;

/*
   AtCoder contest code
   coder : yoichidon
 */

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int K = sc.nextInt();
        long[] h = new long[N];
        for(int n=0; n<N; n++) h[n]=sc.nextLong();

        long[] cost = new long[N];
        Arrays.fill(cost, 5000000000000000L);
        cost[0]=0;

        for(int n=1; n<N;n++){
            for(int k=1;k<=K;k++) if(n-k>=0) {
                cost[n] = Math.min(cost[n], cost[n-k]+Math.abs(h[n]-h[n-k]));
            }
        }

        System.out.println(cost[N-1]);
    }
}
