#include <bits/stdc++.h>

using namespace std;

#define int long long 

const int N = 100010;

int b[N];
int mp[N];

signed main()
{
	int n,a;
	cin >>n>>a;
	int cnt = 0;
	int res = 0;
	int ans = n * 3;
	for(int i = 1;i <= n;i ++)
	{
		cin >>b[i];
	}
	for(int i = 1;i <= n;i ++)
	{
		if(b[i] == 0)mp[i] ++;
		if(b[(i % n) + 1] == 0)mp[i] ++;
		if(b[((i + n - 2) % n) + 1] == 0)mp[i] ++;
	}
	sort(mp + 1,mp + 1 + n);
	for(int i = 1;i <= a;i ++)
	{
		ans -= mp[i];
	}
	cout<<ans;
}