#include <bits/stdc++.h>

using namespace std;

using i64 = long long;

void solve() {
    int n, m;
    cin >> n >> m;
    vector<int>a(n);
    for (int i = 0;i < n;i ++){
        cin >> a[i];
    }
    vector<int>v;
    for (int i = 0;i < n;i ++){
        int cnt = 0;
        cnt += a[i] == 1;
        cnt += (a[(i + 1) % n] == 1);
        cnt += (a[((i + n - 2) % n + 1) % n] == 1);
        // cerr << i << " " << (i + 1) % n << " " << ((i + n - 2) % n + 1) % n<< "\n";
        v.push_back(cnt);
    }
    sort(v.rbegin(), v.rend());
    int ans = 0;
    for (int i = 0;i < m;i ++){
        ans += v[i];
    }
    ans += 3 * (n - m);
    cout << ans << "\n";

}   

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int T = 1;
    // cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}