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

using namespace std;
const int N = 1e5 + 5;
int c[N], d[N];
int op[N];
int sr[N];
bool cmd(int a, int b)
{
	return abs(a) > abs(b);
}
int main(void)
{
	ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
	int n, a;
	cin >> n >> a;
	int suma = 0;
	for (int i = 1; i <= n; i++)
	{
		int x;
		cin >> x;
		sr[i] = x;
		if (x == 1)
		{
			suma++;
		}
		else
		{
			c[i]++;
			c[(i % n) + 1]++;
			c[((i + n - 2) % n) + 1]++;
		}
	}
	sort(c + 1, c + 1 + n, cmd);
	int sumb = n - a;
	int anw = 0;
	for (int i = 1; i <= n; i++)
	{
		if (sumb > 0)
		{
			anw += c[i];
			sumb--;
		}
	}
	cout << anw+suma*3 << endl;
	return 0;
}