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

string to_string(string s) { return s; }
template <typename T> string to_string(T v) {
  bool first = true;
  string res = "[";
  for (const auto &x : v) {
    if (!first)
      res += ", ";
    first = false;
    res += to_string(x);
  }
  res += "]";
  return res;
}

void dbg_out() { cout << endl; }
template <typename Head, typename... Tail> void dbg_out(Head H, Tail... T) {
  cout << ' ' << to_string(H);
  dbg_out(T...);
}

#ifdef DEBUG
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif

signed main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(0);

  int nbPlats, epices;
  cin >> nbPlats >> epices;

  vector<int> peutManger(nbPlats);
  for (int &x : peutManger)
    cin >> x;

  vector<int> choix;
  for (int pos = 0; pos < nbPlats; ++pos) {
    int score = peutManger[pos] + peutManger[(pos + 1) % nbPlats] +
                peutManger[(pos + nbPlats - 1) % nbPlats];
    choix.push_back(score);
  }
  sort(choix.rbegin(), choix.rend());

  int sol = 0;
  for (int i = 0; i < nbPlats; ++i) {
    if (i < epices)
      sol += choix[i];
    else
      sol += 3;
  }
  cout << sol << endl;
}