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.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long INF = 1L << 60;
        int N = sc.nextInt();
        int K = sc.nextInt();
        int[] arr = new int[110000];
        for(int i = 0; i < N; i++) {
            arr[i] = sc.nextInt();
        }

        long[] dp = new long[110000];
        Arrays.fill(dp,INF);
        dp[0] = 0;

        for(int j = 0; j < N; j++) {
            for(int k = 1; k <= K; k++) {
                dp[j+k] = Math.min(dp[j+k],dp[j] + Math.abs(arr[j] - arr[j+k]));
            }
        }
        System.out.println(dp[N-1]);
    }
}
