#include <bits/stdc++.h>
#define endl "\n"
#define int long long
using namespace std;

const int N = 1e5 + 10;
int n, m, a[N], b[N];

void solve()
{
	cin >> n >> m;
	for (int i = 1; i <= n; i++)
	{
		cin >> a[i];
		a[i] ^= 1;
	} 
	for (int i = 1; i <= n; i++)
	{
		b[i] = a[i] + a[i % n + 1] + a[(i + n - 2) % n + 1];
	}
	sort(b + 1, b + 1 + n);
	int ans = 3 * n;
	for (int i = 1; i <= m; i++)
	{
		ans -= b[i];
	}
	cout << ans << endl;
}

signed main()
{
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);

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