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

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int n, a;
    cin >> n >> a;

    vector<int> b(n + 1), c(n + 1);
    for (int i = 1; i <= n; i++) {
    	cin >> b[i];
    }

    for (int i = 1; i <= n; i++) {
    	c[i] = b[i] + b[i % n + 1] + b[(i + n - 2) % n + 1];
    }

    sort(c.begin() + 1, c.end(), greater<int>());
    cout << accumulate(c.begin() + 1, c.begin() + a + 1, 0LL) + (n - a) * 3 << "\n";

    return 0;
}