// what is matter? never mind.
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define int long long
#define ull unsigned long long
using namespace std;
inline int read()
{
	char c=getchar();int x=0;bool f=0;
	for(;!isdigit(c);c=getchar())f^=!(c^45);
	for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
	if(f)x=-x;return x;
}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;
typedef vector<pii>vpii;

#define maxn 2000005
#define inf 0x3f3f3f3f


int n,a,b[maxn],c[maxn];


signed main()
{
	n=read(),a=read();
	For(i,0,n-1)b[i]=read();
	int res=n*3;
	For(i,0,n-1){
		c[i]=(!b[i])+(!(b[(i+1)%n]))+(!(b[(i+n-1)%n]));
	}
	sort(c,c+n);
	For(i,0,a-1)res-=c[i];
	cout<<res;
	return 0;
}