#include <bits/stdc++.h>

using namespace std;

int main() {
    cin.tie(0)->sync_with_stdio(0);

    int n, a; cin >> n >> a;
    vector<int> b(n);
    int S = 0;
    for (int i = 0; i < n; i++) {
        cin >> b[i];
        S += b[i];
    }

    vector<int> affect(n);
    for (int i = 1; i < n - 1; i++) {
        affect[i] = (1 - b[i - 1]) + (1 - b[i]) + (1 - b[i + 1]);
    }
    affect[0] = (1 - b[n - 1]) + (1 - b[0]) + (1 - b[1]);
    affect[n - 1] = (1 - b[0]) + (1 - b[n - 1]) + (1 - b[n - 2]);
    sort(affect.rbegin(), affect.rend());

    int nS = 0;
    for (int i = 0; i < n - a; i++) {
        nS += affect[i];
    }

    cout << S * 3 + nS << "\n";
}