#include <bits/stdc++.h>

using namespace std;

void solve() {
    int n, k;
    cin >> n >> k;
    vector<int>a(n);
    for(int i = 0; i < n; ++i) cin >> a[i];
    vector<int>b(n);
    long long ans = 3 * n;
    for (int i = 0; i < n; ++i) {
        b[i] = a[i] + a[(i + 1) % n] + a[(i + n - 1) % n];
    }
    sort(b.rbegin(), b.rend());
    for (int i = 0; i < k; ++i) ans -= 3 - b[i];
    cout << ans << endl;
}

int main() {
#ifdef DEBUG
    freopen("demo.in", "r", stdin);
    freopen("demo.out", "w", stdout);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    solve();

    return 0;
}