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

const int N=1e5+100;
#define gc getchar()
#define rd read()
inline int read(){
	int x=0,f=0; char c=gc;
	for(;c<'0'||c>'9';c=gc) f|=(c=='-');
	for(;c>='0'&&c<='9';c=gc) x=(x<<1)+(x<<3)+(c^48);
	return f?-x:x;
}

int n,m,ans=0,a[N],b[N];

inline int nx(int x){ return x%n+1; }
inline int pr(int x){ return (x-2+n)%n+1; }

int main(){

	n=rd,m=n-rd;
	for(int i=1;i<=n;++i) a[i]=rd,ans+=3*(a[i]==1);
	for(int i=1;i<=n;++i) b[i]=(a[i]^1)+(a[pr(i)]^1)+(a[nx(i)]^1);
	sort(b+1,b+n+1,[&](int x,int y){ return x>y; });
	for(int i=1;i<=m;++i) ans+=b[i];
	printf("%d\n", ans);

	return 0;
}