#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = double;
constexpr int mod = 998244353;
constexpr int N = 1e6 + 10;

void solve() {
    int n, m;
    cin >> n >> m;
    vector<int> a(n + 1), b(n + 1);
    for (int i = 1; i <= n; i++) cin >> a[i];
    for (int i = 1; i <= n; i++) {
        if (a[i] == 0) {
            b[i]++;
            b[i % n + 1]++;
            b[(i + n - 2) % n + 1]++;
        }
    }
    sort(b.begin() + 1, b.end());
    int ans = 0;
    for (int i = 1; i <= m; i++) {
        ans += b[i];
    }
    cout << 3 * n - ans << "\n";
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int tt = 1;
    // cin >> tt;
    while (tt--) {
        solve();
    }
    return 0;
}