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.Scanner;

public class Main {

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String[] s = sc.nextLine().split(" ");
    int N = Integer.parseInt(s[0]);
    int K = Integer.parseInt(s[1]);
    String[] str = sc.nextLine().split(" ");
    int[] ans = new int[N];
    ans[0] = 0;
    for (int i = 1; i < N; i++) {
      ans[i] = Integer.MAX_VALUE;
    }

    for (int i = 0; i < N; i++) {
      for (int j = i + 1; j <= i + K && j < N; j++) {
        ans[j] =
            Math.min(
                ans[j], Math.abs(Integer.parseInt(str[j]) - Integer.parseInt(str[i])) + ans[i]);
      }
    }
    System.out.println(ans[N - 1]);
  }
}
