#include<iostream>
#include<algorithm>
using namespace std;
int N,K;
long A[2<<17];
long Ls[2<<17];
main()
{
	cin>>N>>K;
	for(int i=0;i<N;i++)cin>>A[i];
	Ls[0]=0;
	for(int i=0;i<N;i++)Ls[i+1]=Ls[i]+A[i];
	long ans=9e18;
	if(K==0)
	{
		ans=min(ans,N*A[0]-Ls[N]);
		ans=min(ans,Ls[N]-N*A[N-1]);
		cout<<ans<<endl;
		return 0;
	}
	for(int a=0;a+K<=N;a++)
	{
		auto calc=[&a](int id)
		{
			if(id<a)
			{
				return -(Ls[N]-Ls[a+K]-(N-a-K)*A[id])
				+(Ls[a+K]-Ls[a]-K*A[id])
				-(Ls[a]-Ls[id]-(a-id)*A[id])
				-(id*A[id]-Ls[id]);
			}
			else if(id<a+K)
			{
				return -(Ls[N]-Ls[a+K]-(N-a-K)*A[id])
				+(Ls[a+K]-Ls[id]-(a+K-id)*A[id])
				+((id-a)*A[id]-(Ls[id]-Ls[a]))
				-(a*A[id]-Ls[a]);
			}
			else
			{
				return -(Ls[N]-Ls[id]-(N-id)*A[id])
				-((id-a-K)*A[id]-(Ls[id]-Ls[a+K]))
				+(K*A[id]-(Ls[a+K]-Ls[a]))
				-(a*A[id]-Ls[a]);
			}
		};
		ans=min(ans,calc(0));
		ans=min(ans,calc(a));
		ans=min(ans,calc(a+K-1));
		ans=min(ans,calc(N-1));
		int L=a,R=a+K-1;
		while(R-L>2)
		{
			int m1=(L+L+R)/3,m2=(L+R+R)/3;
			long f1=calc(m1),f2=calc(m2);
			ans=min(ans,min(f1,f2));
			if(f1<f2)R=m2;
			else L=m1;
		}
		for(int x=L+1;x<R;x++)ans=min(ans,calc(x));
	}
	cout<<ans<<endl;
}