#include <bits/stdc++.h>

#define endl '\n'
#define int long long

using namespace std;

const int maxn = 2e5 + 5;
int n, a;
int c[maxn];
int b[maxn];

void solve() {
    cin >> n >> a;
    for (int i = 1; i <= n; i++)cin >> b[i];
    b[n + 1] = b[1];
    vector<int> v;
    for (int i = 1; i <= n; i++) {
        v.push_back(3 - (b[i] + b[i % n + 1] + b[(i + n - 2) % n + 1]));
    }
    sort(v.begin(), v.end());
    int ans = 3 * n;
//    for(auto x:v)cout<<x<<" ";cout<<endl;
    for (int i = 0; i < a; i++)ans -= v[i];
    cout << ans << endl;
}

signed main() {
    //freopen("../input.txt", "r", stdin);
    cin.tie(nullptr), cout.tie(nullptr);
    ios::sync_with_stdio(false);
    int test = 1;
//    cin >> test;
    while (test--) {
        solve();
    }
    return 0;
}