#include<iostream>
#include<algorithm>
#include<string.h>
#define int long long

using namespace std;

inline int read(){
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0',ch=getchar();}
    return x*f;
}

int n,k;
const int N=1e7+10;
int a[N],ans;

//i mod n + 1
//((i + n - 2) mod n) + 1


int num[N];

signed main(){
    n=read(),k=read();
    for(int i=1;i<=n;i++){
        a[i]=read();
        if(a[i]){
            ans+=3;
        }
        a[i+n]=a[i];
        a[i+n+n]=a[i+n];
        //if(a[i]==0){
        //    q.push_back(i);
        //}
    }
    
    int bula=n-k;
    
    
    int res=0;
    for(int i=1+n;i<=2*n;i++){
            
        res++;
        num[res]=(a[i-1]==0)+(a[i]==0)+(a[i+1]==0);
        //q.push_back(i);

    }
    
    sort(num+1,num+1+res);
    reverse(num+1,num+1+res);
    
    for(int i=1;i<=bula;i++){
        ans+=num[i];
    }
    
    cout<<ans<<endl;
    //for(int i=1;i<=res;i++){
    //    cout<<st[i].num<<" ";
    //}
    
    return 0;
}