#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>

#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

using namespace std;
typedef long long ll;

class MedianTracker{
    public:
    ll sum_l = 0;
    ll sum_r = 0;
    int size = 0;
    void push(ll x){
        str.insert(x);
        sum_r += x;
        size++;
        balance();
    }
    void pop(ll x){
        if(stl.find(x) != stl.end()) {
            stl.erase(stl.find(x));
            sum_l -= x;
        }else{
            str.erase(str.find(x));
            sum_r -= x;
        }
        size--;
        balance();
    }
    ll median(){
        return *str.begin();
    }
    private:
    void balance(){
        while(*str.begin() < *stl.begin()){
            ll x = *stl.begin();
            stl.erase(stl.begin());
            str.insert(x);
            sum_l -= x;
            sum_r += x;
        }
        while(2*str.size() < size){
            ll x = *stl.begin();
            stl.erase(stl.begin());
            str.insert(x);
            sum_l -= x;
            sum_r += x;
        }
        while(2*str.size() > size+1){
            ll x = *str.begin();
            str.erase(str.begin());
            stl.insert(x);
            sum_l += x;
            sum_r -= x;
        }
    }
    multiset<ll, greater<ll>> stl;
    multiset<ll> str;
};

const ll INF = 1e18;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    int n, k; cin >> n >> k;
    vector<ll> a(n);
    for(int i = 0; i < n; i++) cin >> a[i];
    auto mt = MedianTracker();
    ll ans = INF;
    for(int i = 0; i < k; i++) mt.push(a[i]);
    // cout << mt.median() << ' ' << mt.sum_l << ' ' << mt.sum_r << endl;
    int l = k/2, r = k-l;
    chmin(ans, mt.median()*l-mt.sum_l + mt.sum_r-mt.median()*r);
    for(int i = k; i < n; i++){
        mt.push(a[i]);
        mt.pop(a[i-k]);
        chmin(ans, mt.median()*l-mt.sum_l + mt.sum_r-mt.median()*r);
        // cout << mt.median() << ' ' << mt.sum_l << ' ' << mt.sum_r << endl;
    } 
    cout << ans << endl;
}