#include <bits/stdc++.h>
using namespace std;
#define int long long
#define x first
#define y second
#define PII pair<int,int>
const int mod=998244353;
const int N=4e5+100;
int a[N];
void solve(){
	int n,k;
	cin>>n>>k;
	for(int i=1;i<=n;i++) {
		int x;
		cin>>a[i];
	}
	int ans=0,m=n-k;
	vector<int> st(n+10,0);
	vector<PII>nums;
	for(int i=1;i<=n;i++)
	{
		int res=0;
		for(int j=-1;j<=1;j++)
		{
			int t = i + j;
			if(t==n+1)	t=0;
			if(t==0)	t=n;
			if(!a[t])	res++;
		}
		nums.push_back({res,i});
	}
	sort(nums.begin(),nums.end());
	reverse(nums.begin(),nums.end());
	for(int i=0;i<m;i++)
		st[nums[i].y]=1;
	for(int i =1;i<=n;i++)
		if(!a[i])
		{
			for(int j=-1;j<=1;j++)
			{
				int t = i + j;
				if(t==n+1)	t=0;
				if(t==0)	t=n;
				if(st[t])	ans++;
			}
		}
		else	ans+=3;
	cout<<ans<<endl;
}
signed main() {
	int T=1;
//	freopen("C:\\Users\\86153\\Desktop\\data.in.txt","r",stdin); //´ÓÎļþÖлñÈ¡ÊäÈëÁ÷
//	freopen("C:\\Users\\86153\\Desktop\\data1.out.txt","w",stdout); //°ÑÊä³öתµ½ÎļþÖÐ
	//init();
	//cin>>T;
	while(T--) {
		solve();
	}
	//return 0;
}