/*
 * author:  ADMathNoob
 * created: 04/08/23 14:06:11
 * problem: https://qoj.ac/problem/6310
 */

/*
Comments about problem:

In-contest submission.

I can't believe I read this problem first and skipped over it.
*/

#include <bits/stdc++.h>

using namespace std;

#ifdef _DEBUG
#include "../.cp/algorithms/debug/debug.h"
#else
#define debug(...) 42
#endif

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, s;
  cin >> n >> s;
  vector<int> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  vector<int> cnt(n);
  for (int i = 0; i < n; i++) {
    cnt[i] = a[i] + a[(i + 1) % n] + a[(i + 2) % n];
  }
  sort(cnt.rbegin(), cnt.rend());
  int ans = 0;
  for (int i = 0; i < s; i++) {
    ans += cnt[i];
  }
  ans += 3 * (n - s);
  cout << ans << '\n';
  return 0;
}