import java.util.*;


import java.io.*;



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

	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz