#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

const int MAXN=1e5;

int A[MAXN];
int n,k;

void init(){
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;i++) scanf("%d",&A[i]);
}

typedef long long LL;
LL ans=(LL)2147483647*100000LL;

LL min(LL a,LL b){
	if(a>b) return b;
	return a;
}

LL update(int st,int en){
	LL res=0;
	for(int i=st;i<=en;i++)
		for(int j=i+1;j<=en;j++) res+=abs(A[i]-A[j]);
	return res;
}

void work(){
	ans=update(1,k);
	for(int i=k+1;i<=n;i++)//End
		ans=min(ans,update(i-k+1,i));
	cout<<ans<<endl;
}

int main(){
	freopen("qwa.in","r",stdin);
	freopen("qwa.out","w",stdout);
	init();
	work();
	return 0;
}