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.*;

public class Main{

    final long mo=(long)1e9+7;
    
    public static void main(String[] args){
		new Main().run();
    }

    void run(){
      Scanner sc=new Scanner(System.in);
      int N=sc.nextInt();
      int K=sc.nextInt();
      long[] H=new long[N];
      for(int i=0;i<N;++i){
          H[i]=sc.nextLong();
      }
      long[] cost=new long[N];
      Arrays.fill(cost,1L<<60);
      cost[0]=0;
      for(int i=0;i<N;++i){
          for(int j=1;j<=K&&i+j<N;++j){
    	      cost[i+j]=Math.min(cost[i+j],cost[i]+Math.abs(H[i]-H[i+j]));
          }
      }
      System.out.println(cost[N-1]);
    }
}
