import java.io.*;
import java.util.*;

public class Main {
 	public static void main(String args[]) throws IOException {
     	Scan sc = new Scan();
      	int N = sc.scanInt();
      	int K = sc.scanInt();
      	int[] height = new int[N];
      	for(int i=0;i<N;i++) {
         	height[i] = sc.scanInt(); 
        }
      	int[] dp = new int[N];
      	dp[0] = 0;
      	for(int i=1;i<=K && i<N ;i++) {
          	dp[i] = Integer.MAX_VALUE;
        	for(int j=0;j<i;j++) {
             	dp[i] = Math.min(dp[j] + Math.abs(height[j] - height[i]), dp[i]);
            }
        }
      for(int i=K+1;i<N;i++) {
        dp[i] = Integer.MAX_VALUE;
        for(int j=i-K;j<i;j++) {
          dp[i] = Math.min(dp[j] + Math.abs(height[j] - height[i]), dp[i]);
        }
      }
      	System.out.println(dp[N-1]);
    }
}

class Scan
{
    private byte[] buf=new byte[1024];
    private int index;
    private InputStream in;
    private int total;
    public Scan()
    {
        in=System.in;
    }
    public int scan()throws IOException
    {
        if(total<0)
        throw new InputMismatchException();
        if(index>=total)
        {
            index=0;
            total=in.read(buf);
            if(total<=0)
            return -1;
        }
        return buf[index++];
    }
    public int scanInt()throws IOException
    {
        int integer=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n))
        {
            if(n>='0'&&n<='9')
            {
                integer*=10;
                integer+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        return neg*integer;
    }
    public double scanDouble()throws IOException
    {
        double doub=0;
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        int neg=1;
        if(n=='-')
        {
            neg=-1;
            n=scan();
        }
        while(!isWhiteSpace(n)&&n!='.')
        {
            if(n>='0'&&n<='9')
            {
                doub*=10;
                doub+=n-'0';
                n=scan();
            }
            else throw new InputMismatchException();
        }
        if(n=='.')
        {
            n=scan();
            double temp=1;
            while(!isWhiteSpace(n))
            {
                if(n>='0'&&n<='9')
                {
                    temp/=10;
                    doub+=(n-'0')*temp;
                    n=scan();
                }
                else throw new InputMismatchException();
            }
        }
        return doub*neg;
    }
    public String scanString()throws IOException
    {
        StringBuilder sb=new StringBuilder();
        int n=scan();
        while(isWhiteSpace(n))
        n=scan();
        while(!isWhiteSpace(n))
        {
            sb.append((char)n);
            n=scan();
        }
        return sb.toString();
    }
    private boolean isWhiteSpace(int n)
    {
        if(n==' '||n=='\n'||n=='\r'||n=='\t'||n==-1)
        return true;
        return false;
    }
}


Measured memory_bytes: 33884