using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;

namespace DP
{
    using static Ex;
    public class Solve
    {
        public static void Main(string[] args)
        {
            new DP_B();
        }
    }
    public class DP_A
    {
        public DP_A()
        {
            var n = ReadInt;
            var arr = ReadIntArray();
            var dp = new long[n];

            for (int i = 0; i < n; i++)
            {
                dp[i] = long.MaxValue;
            }
            dp[0] = 0;
            for (int i = 0; i < n; i++)
            {
                var j = i + 1;
                if (j < n) dp[j] = Math.Min(dp[j], dp[i] + Math.Abs(arr[i] - arr[j]));
                j = i + 2;
                if (j < n) dp[j] = Math.Min(dp[j], dp[i] + Math.Abs(arr[i] - arr[j]));
            }

            dp[n - 1].Cw();
        }
    }
    public class DP_B
    {
        public DP_B()
        {
            var l = ReadIntArray();
            var n = l[0];
            var K = l[1];
            var arr = ReadIntArray();
            var dp = new long[n];

            for (int i = 0; i < n; i++)
            {
                dp[i] = long.MaxValue;
            }
            dp[0] = 0;
            for (int i = 0; i < n; i++)
            {
                for (int k = 1; k <= K; k++)
                {
                    var j = i + k;
                    if (j < n) dp[j] = Math.Min(dp[j], dp[i] + Math.Abs(arr[i] - arr[j]));
                }
            }

            dp[n - 1].Cw();
        }
    }

    public static class Ex
    {
        public static void Cw(this object s) { Console.WriteLine(s); }



        public static bool Mins<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) > 0) { a = b; return true; } return false; }
        public static bool Maxs<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) < 0) { a = b; return true; } return false; }
        public static void Swap<T>(ref T a, ref T b) { var t = b; b = a; a = t; }
        public static void Swap<T>(List<T> list, int i, int j) { T tmp = list[j]; list[j] = list[i]; list[i] = tmp; }


        static long Gcd(long m, long n) { if (n == 0) return m; return Gcd(n, m % n); }
        public static List<string> FastSort(this List<string> s) { s.Sort(StringComparer.Ordinal); return s.ToList(); }
        public static void yesno(this bool b) { (b ? "yes" : "no").Cw(); }
        public static void YesNo(this bool b) { (b ? "Yes" : "No").Cw(); }
        public static void YESNO(this bool b) { (b ? "YES" : "NO").Cw(); }

        public static string Read { get { return Console.ReadLine().Trim(); } }
        public static int ReadInt { get { return int.Parse(Read); } }
        public static long ReadLong { get { return long.Parse(Read); } }
        public static double ReadDouble { get { return double.Parse(Read); } }
        public static string[] ReadArray() { return Read.Split(' '); }
        public static int[] ReadIntArray() { return Read.Split(' ').Select(int.Parse).ToArray(); }
        public static long[] ReadLongArray() { return Read.Split(' ').Select(long.Parse).ToArray(); }
        public static string[] ReadArray(long N) { var v = new string[N]; for (long i = 0; i < N; ++i) v[i] = Read; return v; }
        public static int[] ReadIntArray(long N) { var v = new int[N]; for (long i = 0; i < N; ++i) v[i] = ReadInt; return v; }
        public static long[] ReadLongArray(long N) { var v = new long[N]; for (long i = 0; i < N; ++i) v[i] = ReadLong; return v; }

    }
}

Measured memory_bytes: 20448