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

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        int[] a = new int[n];
        for(int i=0;i<n;i++){
            a[i] = sc.nextInt();
        }
        int[] dp = new int[n];
        Arrays.fill(dp, Integer.MAX_VALUE);
        dp[0] = 0;
        for(int i=0;i<n;i++){
            for(int j=1;j<=k && i+j<n;j++){
                dp[i+j] = Math.min(dp[i+j], dp[i]+Math.abs(a[i+j]-a[i]));
            }
        }
        System.out.println(dp[n-1]);
    }
}