#!/usr/bin/env python
from __future__ import division, print_function

import os
import sys
from io import BytesIO, IOBase

if sys.version_info[0] < 3:
    from __builtin__ import xrange as range
    from future_builtins import ascii, filter, hex, map, oct, zip

from math import sqrt, floor, factorial, gcd
from collections import deque, Counter, defaultdict


# region fastio

BUFSIZE = 8192


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


def print(*args, **kwargs):
    """Prints the values to a stream, or to sys.stdout by default."""
    sep, file = kwargs.pop("sep", " "), kwargs.pop("file", sys.stdout)
    at_start = True
    for x in args:
        if not at_start:
            file.write(sep)
        file.write(str(x))
        at_start = False
    file.write(kwargs.pop("end", "\n"))
    if kwargs.pop("flush", False):
        file.flush()


if sys.version_info[0] < 3:
    sys.stdin, sys.stdout = FastIO(sys.stdin), FastIO(sys.stdout)
else:
    sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)

input = lambda: sys.stdin.readline().rstrip("\r\n")
read = lambda: list(map(int, input().split(" ")))
# endregion



def solve():
    n, k =read(); arr = read()
    dp = [10**9 for i in range(n)]; dp[0] = 0
    for i in range(n):
    	for j in range(1, k+1):
    		if i-j >-1:
    			dp[i] = min(dp[i], dp[i-j]+abs(arr[i-j] - arr[i]))
    # print(dp)
    print(dp[-1])

    

if __name__ == "__main__":
	solve()

### FIXED CODE ###

import sys
# import numpy as np
inp = sys.stdin.readline
read = lambda: list(map(int, inp().strip().split()))
# import profile

def solve():
    n, k =read(); arr = read()
    dp = [-1]*n; dp[0] = 0
    for i in range(n):
    	for j in range(1, k+1):
    		if i-j >-1:
    			tem = dp[i-j]+abs(arr[i-j] - arr[i])
    			if dp[i] == -1:
    				dp[i] = tem
    			elif dp[i] > tem:
    				dp[i] = tem
    				# dp[i] = min(dp[i], tem)
    print(dp[-1])

def one():
	l = [0]*10**7
def two():
	l = [0 for i in range(10**7)]

if __name__ == "__main__":
	solve()
	# cProfile.run(solve())
	# profile.run(one())
	# cProfile.run()