// written by Eng. Abdullah Haydari
#include <bits/stdc++.h>
using namespace std;
int main(){
    int n,k; cin>>n>>k;
    int h[n],memo[n];
    memo[n-1]=0;
    for (int i=0;i<n;i++)
        cin>>h[i];
    for (int i=n-2;i>=0;i--){
        memo[i]=2e9;
        for (int j=1;j<=k and i+j<n;j++){
            int cost=memo[i+j]+abs(h[i]-h[i+j]);
            if (cost<memo[i])
                memo[i]=cost;
        }
    }
    cout<<memo[0]<<endl;
}

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