#include <bits/stdc++.h>
using namespace std;

template<typename T>
class MedianHeap{
private:
    T deviation;
    multiset<T> Ls;
    multiset<T> Rs;
    void adjust(){
        if (Ls.size() < Rs.size()){
            Ls.insert(*Rs.begin());
            Rs.erase(Rs.begin());
        }else if(Ls.size() > Rs.size() + 1){
            Rs.insert(*Ls.rbegin());
            Ls.erase(--Ls.end());
        }
    }
public:
    MedianHeap(const vector<T> & src): deviation(0){
        vector<T> tmp(src);
        sort(tmp.begin(), tmp.end());
        int n_L = src.size() - src.size() / 2;
        T med = *(tmp.begin() + n_L - 1);
        for (auto v : tmp) deviation += abs(v - med);
        Ls.insert(tmp.begin(), tmp.begin() + n_L);
        Rs.insert(tmp.begin() + n_L, tmp.end());
    }
    T median(){
        if (Ls.size() > Rs.size()){
            assert(Ls.size() == Rs.size() + 1);
            return *Ls.rbegin();
        }else{
            assert(Ls.size() == Rs.size());
            return (*Ls.rbegin() + *Rs.begin()) / 2LL;
        }
    }
    void insert(T v){
        T prev_med = this->median();
        if (v <= prev_med){
            Ls.insert(v);
        }else{
            Rs.insert(v);
        }
        this->adjust();
        if (Ls.size() > Rs.size()){
            deviation += abs(this->median() - v);
        }else{
            deviation += abs(prev_med - v);
        }
    }
    bool erase(T v){
        T prev_med = this->median();
        if (v > prev_med){
            auto it = Rs.find(v);
            if (it == Rs.end()) return false;
            Rs.erase(it);
        }else{
            auto it = Ls.find(v);
            if (it == Ls.end()) return false;
            Ls.erase(it);
        }
        this->adjust();
        if (Ls.size() > Rs.size()){
            deviation -= abs(this->median() - v);
        }else{
            deviation -= abs(prev_med - v);
        }
        return true;
    }
    T get_deviation(){
        return this->deviation;
    }
};


long long solve(int N, int K, const vector<long long> & As){
    vector<long long> src(As.begin(), As.begin() + K);
    MedianHeap<long long> mh(src);
    long long record = mh.get_deviation();
    for (int i = K; i < N; ++i){
        mh.insert(As[i]);
        if (not mh.erase(As[i - K])){
            cout << "Erase Failed! val = " << As[i - K] << endl;
        };
        record = min(record, mh.get_deviation());
    }
    return record;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N, K;
    cin >> N >> K;
    vector<long long> As(N, 0);
    for (auto & a : As) cin >> a;
    cout << solve(N, K, As) << endl;
    return 0;
}