#include <bits/stdc++.h>
using namespace std;

template <class T> using V = vector<T>;
template <class T> using VV = V<V<T>>;

using ll = int64_t;

const int N=1e5+5;
int n,k;
int a[N],b[N];
inline bool cmp(int x,int y)
{
	return x>y;
}

int main() {
	ios_base::sync_with_stdio(false), cin.tie(nullptr);
	cout << fixed << setprecision(20);
	cin>>n>>k;
	for(int i=1;i<=n;i++) cin>>a[i];
	for(int i=1;i<=n;i++) 
	{
		int lef=i-1;
		if(lef==0) lef=n;
		int rig=i+1;
		if(rig==n+1) rig=1;
		b[i]=(a[lef]==1) + (a[i]==1) + (a[rig]==1);
	}
	sort(b+1,b+n+1,cmp);
	int ans=0;
	for(int i=1;i<=k;i++) ans+=b[i];
	//for(int i=k+1;i<=n;i++) ans+=(3-b[i]);
	ans+=(n-k)*3;
	cout<<ans<<endl;
	return 0;
}