#include<bits/stdc++.h>
using namespace std;
#define int long long  
int v[4];
signed main (){
	std::ios::sync_with_stdio(false);  
	cin.tie(NULL); 
	cout.tie(NULL);
	int n,a;
	cin>>n>>a;
	vector<int> c(n+3);
	int ans = 0;
	for(int i=1;i<=n;i++)
	{
		cin>>c[i];
		if(c[i]==1)
			ans +=3;
	}
	c[n+1] = c[1];
	c[n+2] = c[2];

	for(int i=2;i<=n+1;i++)
	{
		int num = 0;
		if(c[i-1]==0)
			num++;
		if(c[i]==0)
			num++;
		if(c[i+1]==0)
			num++;
		v[num]++;
	}
	a = n-a;
	int l = 3;
	while(a--)
	{	v[l]--;
		
		while(v[l]<=0)
			l--;
		
		ans +=l;
	}
	cout<<ans<<endl;
	
}