#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
using i64 = long long;
void solve()
{
    int n, a;
    cin >> n >> a;
    vector<int> f(n), g(n);
    for (int i = 0; i < n; i++)
        cin >> f[i];
    for (int i = 0; i < n; i++)
    {
        g[i] += (f[(i - 1 + n) % n] == 0);
        g[i] += (f[(i + 1) % n] == 0);
        g[i] += (f[i] == 0);
    }
    sort(g.begin(), g.end());
    i64 ans = 0;
    for (int i = n - a - 1; i < n; i++)
        ans += g[i];
    for (int i = 0; i < n; i++)
        ans += (f[i] == 1 ? 3 : 0);
    cout << ans << endl;
}
signed main()
{
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    int tc = 1;
    // cin >> tc;
    while (tc--)
        solve();
    return 0;
}