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

     long [] dp=new long[n];

     dp[0]=0;
    
     for(int i=1;i<n;i++){

       long min=Integer.MAX_VALUE;

       for(int j=i-1;j>=i-k && j>=0;j--){

         min=Math.min(min,dp[j]+Math.abs(arr[i]-arr[j]));

       }
       dp[i]=min;
     }

     System.out.println(dp[n-1]);

    }
   }
 