/*
LANG:C++
TASK:bus
*/

#include <iostream>
#include <cmath>

using namespace std;

int n,k,i,a[1024],srt[1024][1024],top[1024],mx=0,res[1024],rtop=0,j,ind=0,sum=0,u[1024],t;
bool dont=0;
int main()
{
	cin>>n>>k;
	cin>>a[0];
	for(i=1;i<n-1;i++)
	{
		cin>>a[i];
		srt[a[i]][top[a[i]]++]=i;
		if(a[i]>mx)
			mx=a[i];
	}
	cin>>a[n-1];
	res[rtop++]=1;
	res[rtop++]=n;
	k-=2;
	for(i=mx;i>=0;i--)
		for(j=0;j<top[i];j++)
		{
			if(!k)
				break;
			dont=0;
			for(t=-4;t<4;t++)
				if((srt[i][j]+t>=0)&&(u[t+srt[i][j]]))
				{
					dont=1;
					break;
				}
			if(dont)
				continue;
			u[srt[i][j]]=1;
			res[rtop++]=srt[i][j]+1;
			k--;
		}
	sort(res,res+rtop);
/*	for(i=0;i<rtop;i++)
		cout<<res[i]<<" ";
	cout<<"\n"; */
	for(i=1;i<=n;i++)
	{
		if(abs(res[ind]-i)>abs(res[ind+1]-i))
			ind++;
		j=res[ind]-i;
//		cout<<i<<" "<<res[ind]<<"\n";
		sum+=a[i-1]*max(j,-j);
//		cout<<a[i-1]*max(j,-j)<<"\n";
	}
	cout<<sum<<"\n";
	return 0;
}
