#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------

int N,K;
ll A[202020],S[202020];

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>K;
	FOR(i,N) {
		cin>>A[i];
		S[i+1]=S[i]+A[i];
	}
	
	ll ret=1LL<<60;
	if(K<=1) {
		ll a=0,b=0;
		FOR(i,N) {
			a+=-abs(A[i]-A[0]);
			b+=-abs(A[i]-A[N-1]);
		}
		ret=min(a,b);
	}
	else {
		int L=0,R=K-1;
		FOR(i,N) {
			while(R<N-1&&(A[i]-A[L])>=(A[R+1]-A[i])) R++,L++;
			ll tmp=((S[R+1]-S[i+1])-A[i]*(R-i))-((S[N]-S[R+1])-A[i]*(N-(R+1)));
			tmp+=(A[i]*(i-L)-(S[i]-S[L]))-(L*A[i]-S[L]);
			ret=min(ret,tmp);
		}
		
	}
	cout<<ret<<endl;
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}