#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define endl "\n"
#define mod 1000000007
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
typedef unordered_map<int, int> umap;
void inputarr(int arr[], int n) {REP(i, 0, n) {cin >> arr[i];}}
int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n,k;
	cin>>n>>k;
	int arr[n];
	inputarr(arr,n);
	vector<int>dp(n,0);
	dp[0]=0;
	dp[1]=abs(arr[1]-arr[0]);
	for(int i=2;i<n;i++){
	  dp[i]=INT_MAX;
	  for(int j=1;j<=k;j++){
	    if(i-k>=0){
	      dp[i] = min(dp[i-k] + abs(arr[i]-arr[i-k]),dp[i]);
	    }
 
	  }
	 // int c1 = abs(arr[i-1]-arr[i])+dp[i-1];
	 // int c2 = abs(arr[i-2]-arr[i])+dp[i-2];
 
	}
	cout<<dp[n-1];
 
}

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