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

long long solve_odd(int N, int K, const vector<long long> & As){
    int w = K / 2;
    vector<long long> Bs(As.begin(), As.begin() + K);
    sort(Bs.begin(), Bs.end());
    long long med = Bs[w];
    multiset<long long> Ls(Bs.begin(), Bs.begin() + w);
    multiset<long long> Rs(Bs.begin() + w + 1, Bs.end());
    long long cost = 0;
    for (auto b : Bs) cost += abs(b - med);
    long long best = cost;
    for (int i = K; i < N; ++i){
        long long vin = As[i];
        long long vout = As[i - K];
        if (med < vin and med < vout){
            Rs.insert(vin);
            auto it = Rs.find(vout);
            Rs.erase(it);
            cost += vin - vout;
        }else if (vin <= med and vout <= med){
            Ls.insert(vin);
            auto it = Ls.find(vout);
            Ls.erase(it);
            cost += vout - vin;
        }else if (vin <= med and med < vout){
            Rs.insert(med);
            auto it = Rs.find(vout);
            Rs.erase(it);
            cost += med - vout;
            med = *Ls.rbegin();
            Ls.insert(vin);
            it = Ls.find(med);
            Ls.erase(it);
            cost += med - vin;
        }else if (med < vin and vout <= med){
            Ls.insert(med);
            auto it = Ls.find(vout);
            Ls.erase(it);
            cost += vout - med;
            med = *Rs.begin();
            Rs.insert(vin);
            it = Rs.find(med);
            Rs.erase(it);
            cost += vin - med;
        }
        best = min(best, cost);
    }
    return best;
}

long long solve_even(int N, int K, const vector<long long> & As){
    int w = K / 2;
    vector<long long> Bs(As.begin(), As.begin() + K);
    sort(Bs.begin(), Bs.end());
    long long medL = Bs[w - 1];
    long long medR = Bs[w];
    long long med = (medL + medR) / 2LL;
    multiset<long long> Ls(Bs.begin(), Bs.begin() + w);
    multiset<long long> Rs(Bs.begin() + w, Bs.end());
    long long cost = 0;
    for (auto b : Bs) cost += abs(b - med);
    long long best = cost;
    for (int i = K; i < N; ++i){
        long long vin = As[i];
        long long vout = As[i - K];
        if (medL < vin and medR <= vout){
            Rs.insert(vin);
            auto it = Rs.find(vout);
            Rs.erase(it);
            cost += vin - vout;
        }else if (vin <= medR and vout <= medL){
            Ls.insert(vin);
            auto it = Ls.find(vout);
            assert(it != Ls.end());
            Ls.erase(it);
            cost += vout - vin;
        }else if (vin <= medR and medR <= vout){
            Rs.insert(medL);
            auto it = Rs.find(vout);
            Rs.erase(it);
            cost += medL - vout;
            Ls.insert(vin);
            it = Ls.find(medL);
            Ls.erase(it);
            cost += medL - vin;
        }else if (medL < vin and vout <= medL){
            Ls.insert(medR);
            auto it = Ls.find(vout);
            Ls.erase(it);
            cost += vout - medR;
            Rs.insert(vin);
            it = Rs.find(medR);
            Rs.erase(it);
            cost += vin - medR;
        }
        best = min(best, cost);
        medL = *Ls.rbegin();
        medR = *Rs.begin();
    }
    return best;
}

long long solve(int N, int K, const vector<long long> & As){
    if (K % 2 == 1){
        return solve_odd(N, K, As);
    }else{
        return solve_even(N, K, As);
    }
}

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;
}