#include <algorithm>
#include <iostream>
#include <vector>
#include <set>

using namespace std;

const long long INF = 1LL<<60;

int n, k;
int a[100000];

struct Middler {
  int n;
  int mid;
  multiset<int> pref;
  multiset<int> suff;
  long long psum;
  long long ssum;

  Middler(const vector<int> &v) {
    n = v.size();
    int j = v.size() / 2;
    mid = v[j];

    psum = 0;
    for (int i = 0; i < j; i++) {
      pref.insert(v[i]);
      psum += v[i];
    }

    ssum = 0;
    for (int i = j+1; i < n; i++) {
      suff.insert(v[i]);
      ssum += v[i];
    }
  }

  void shiftLeft() {
    pref.insert(mid);
    psum += mid;
    auto itr = suff.begin();
    mid = *itr;
    suff.erase(itr);
    ssum -= mid;
  }

  void shiftRight() {
    suff.insert(mid);
    ssum += mid;
    auto v = pref.end();
    mid = *--v;
    pref.erase(v);
    psum -= mid;
  }

  void normalize() {
    while (pref.size() < suff.size())
      shiftLeft();
    while (pref.size() > suff.size() + 1)
      shiftRight();
  }

  void pop(int x) {
    if (x == mid) {
      auto itr = pref.end();
      mid = *--itr;
      pref.erase(itr);
      psum -= mid;
    } else if (x < mid) {
      auto itr = pref.find(x);
      pref.erase(itr);
      psum -= x;
    } else {
      auto itr = suff.find(x);
      suff.erase(itr);
      ssum -= x;
    }
    normalize();
  }

  void push(int x) {
    if (x <= mid) {
      pref.insert(x);
      psum += x;
    } else {
      suff.insert(x);
      ssum += x;
    }
    normalize();
  }

  void debug(const string &msg) {
    cout << msg << endl;
    cout << mid << endl;
    cout << pref.size() << " " << psum << " ";
    for (auto &t: pref)
      cout << t << " ";
    cout << endl;
    cout << suff.size() << " " << ssum << " ";
    for (auto &t: suff)
      cout << t << " ";
    cout << endl;
  }
  
};

int main() {
  cin >> n >> k;
  for (int i = 0; i < n; i++)
    cin >> a[i];

  if (k == 1) {
    cout << 0 << endl;
    return 0;
  }
  
  vector<int> v(k);
  for (int i = 0; i < k; i++)
    v[i] = a[i];
  sort(v.begin(), v.end());

  Middler middler(v);

  long long ret = INF;
  for (int i = 0; i < n; i++) {
    long long sum =
      (middler.mid * middler.pref.size() - middler.psum) +
      (middler.ssum - middler.mid * middler.suff.size());
    ret = min(ret, sum);
    if (i+k >= n) break;
    middler.pop(a[i]);
    middler.push(a[i+k]);
  }

  cout << ret << endl;
  
  return 0;
}