#include <cstdio>
#include <cstring>
#include <string>
#include <iostream>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <unordered_map>
#include <unordered_set>
#include <random>
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

random_device rnd;
mt19937 mt(rnd());
uniform_real_distribution<> rnd1(0, 1.0);

struct node_t{
	ll val;
	ll sum;
	node_t *lch;
	node_t *rch;
	double pri;
	int cnt;
	node_t() {}
	node_t(ll v, double p):val(v), pri(p), cnt(1), sum(v), lch(nullptr), rch(nullptr){}

};

int count(node_t *t){
	return !t ? 0 : t->cnt;
}

ll sum(node_t *t){
	return !t ? 0 : t->sum;
}

node_t *update(node_t *t){
	t->cnt=count(t->lch)+count(t->rch)+1;
	t->sum=sum(t->lch)+sum(t->rch)+(t->val);
	return t;
}

node_t *merge(node_t *l, node_t *r){
	if(!l || !r) return !l ? r : l;
	if(l->pri > r->pri){
		l->rch=merge(l->rch, r);
		return update(l);
	}else{
		r->lch=merge(l, r->lch);
		return update(r);
	}
}

pair<node_t*, node_t*> split(node_t *t, ll x){
	if(!t) return make_pair(nullptr, nullptr);
	if(x <= t->val){
		pair<node_t*, node_t*> s=split(t->lch, x);
		t->lch=s.second;
		return make_pair(s.first, update(t));
	}else{
		pair<node_t*, node_t*> s=split(t->rch, x);
		t->rch=s.first;
		return make_pair(update(t), s.second);
	}
}

pair<node_t*, node_t*> split2(node_t *t, int k){ //[0, k), [k,n)
	if(!t) return make_pair(nullptr, nullptr);
	if(k <= count(t->lch)){
		pair<node_t*, node_t*> s=split2(t->lch, k);
		t->lch=s.second;
		return make_pair(s.first, update(t));
	}else{
		pair<node_t*, node_t*> s=split2(t->rch, k-1-count(t->lch));
		t->rch=s.first;
		return make_pair(update(t), s.second);
	}
}

node_t *insert(node_t *t, ll x){
	pair<node_t*, node_t*> s=split(t, x);
	return merge(merge(s.first, new node_t(x, rnd1(mt))), s.second);
}

node_t *erase(node_t *t, int k){
	pair<node_t*, node_t*> s=split2(t, k);
	pair<node_t*, node_t*> s2=split2(s.second, 1);
	return merge(s.first, s2.second);
}

ll find(node_t *t, int k){
	if(count(t->lch)==k){
		return t->val;
	}else if(count(t->lch)<k){
		return find(t->rch, k-count(t->lch)-1);
	}else{
		return find(t->lch, k);
	}
}

void find2(node_t *t, ll x, int& ans){
	if(x==(t->val)){
		ans+=count(t->lch);
		return;
	}else if(x<(t->val)){
		return find2(t->lch, x, ans);
	}else{
		ans+=(count(t->lch)+1);
		return find2(t->rch, x, ans);
	}
}

ll calc(node_t *t, int k){
	ll x=find(t, k);
	pair<node_t*, node_t*> s=split2(t, k);
	ll s1=sum(s.first), s2=sum(s.second);
	ll ans=x*(ll)k-s1+s2-x*(ll)(count(s.second));
	t=merge(s.first, s.second);
	return ans;
}

int main()
{
	int n, k; cin>>n>>k;
	ll a[100000];
	for(int i=0; i<n; i++){
		cin>>a[i];
	}
	node_t *s=nullptr;
	for(int i=0; i<k; i++){
		s=insert(s, a[i]);
	}
	ll ans=calc(s, k/2);
	for(int i=k; i<n; i++){
		s=insert(s, a[i]);
		int ct=0;
		find2(s, a[i-k], ct);
		s=erase(s, ct);
		ans=min(ans, calc(s, k/2));
	}
	cout<<ans<<endl;
    return 0;
}