#include <cstdio>
#include <algorithm>
#include <numeric>
#include <functional>
using namespace std;

const int N = 300005;

int wt[N];

int main() {
  int n, a;
  scanf("%d%d", &n, &a);
  for (int i = 0; i < n; ++i) {
    int x;
    scanf("%d", &x);
    wt[(i + 1) % n] += x;
    wt[i] += x;
    wt[(i + n - 1) % n] += x;
  }
  sort(wt, wt + n, greater<int>());
  printf("%d\n", 3 * (n - a) + accumulate(wt, wt + a, 0));
}