#include <iostream>
#include<bits/stdc++.h>

using namespace std;

int main() {
	int n;
	cin>>n;
	int k;
	cin>>k;
	
	vector<int> h(n+1,0);
	for(int i=1;i<=n;i++){
		cin>>h[i];
	}
	
	vector<int> dp(n+1,INT_MAX);
	dp[1]=0;
	dp[2]=abs(h[2]-h[1]);
	for(int i=3;i<=n;i++){
		
		int j=1;
		while(j<=k && i-j>=1){
		dp[i] = min(dp[i] , abs(h[i-j] - h[i]) + dp[i-j]);
		j++;
		}
	}
	
	cout<<dp[n];
	
	return 0;
}