#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

using mint = modint1000000007;

void debug_mint1(vector<mint> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        cerr << vec[i].val() << " ";
    }
    cerr << endl;
}

void debug_mint2(vector<vector<mint>> &vec) {
    for (int i = 0; i < vec.size(); i++) {
        for (int j = 0; j < vec[i].size(); j++) {
            cerr << vec[i][j].val() << " ";
        }
        cerr << endl;
    }
}

ll INF = 1000000000000000023LL;

int main() {
    ll N, K;
    cin >> N >> K;
    vector<ll> A(N);
    rep(i, N){
        cin >> A[i];
    }
    vector<ll> sums(N + 1);
    rep(i, N){
        sums[i + 1] = sums[i] + A[i];
    }

    // debug(sums);

    // たぶん端に寄せるパターンだけ試せば良さそう
    // -1 が先に来るパターン
    ll ans = INF;

    for (ll i = 0; i < N - K; i++){
        ll score_sub = 0;
        score_sub -= (i * A[i] - sums[i]);
        score_sub -= (sums[N - K] - sums[i] - (N - K - i) * A[i]);
        score_sub += (sums[N] - sums[N - K] - K * A[i]);
        // debug_out(i, score_sub);
        ans = min(ans, score_sub);
    }
    for (ll i = N - K; i < N; i++){
        ll score_sub = 0;
        score_sub -= ((N - K) * A[i] - (sums[N - K] - sums[0]));
        score_sub += ((i - (N - K)) * A[i] - (sums[i] - sums[N - K]));
        score_sub += (sums[N] - sums[i] - (N - i) * A[i]);
        // debug_out(i, score_sub);
        ans = min(ans, score_sub);
    }

    // 1 が先に来るパターン
    for (ll i = 0; i < K; i++){
        ll score_sub = 0;
        score_sub += (i * A[i] - sums[i]);
        score_sub += (sums[K] - sums[i] - (K - i) * A[i]);
        score_sub -= (sums[N] - sums[K] - (N - K) * A[i]);
        // debug_out(i, score_sub);
        ans = min(ans, score_sub);
    }
    for (ll i = K; i < N; i++){
        ll score_sub = 0;
        score_sub += (K * A[i] - (sums[K] - sums[0]));
        score_sub -= ((i - K) * A[i] - (sums[i] - sums[K]));
        score_sub -= (sums[N] - sums[i] - (N - i) * A[i]);
        // debug_out(i, score_sub);
        ans = min(ans, score_sub);
    }

    cout << ans << endl;
}