//μ's forever
#include <bits/stdc++.h>
#define N 100005
//#define getchar nc
using namespace std;
inline char nc(){
    static char buf[100000],*p1=buf,*p2=buf;
    return p1==p2&&(p2=(p1=buf)+fread(buf,1,100000,stdin),p1==p2)?EOF:*p1++;
}
inline int read()
{
    register int x=0,f=1;register char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9')x=(x<<3)+(x<<1)+ch-'0',ch=getchar();
    return x*f;
}
inline void write(register int x)
{
    if(!x)putchar('0');if(x<0)x=-x,putchar('-');
    static int sta[20];register int tot=0;
    while(x)sta[tot++]=x%10,x/=10;
    while(tot)putchar(sta[--tot]+48);
}
int n,a,b[N],c[N];
int main()
{
    n=read(),a=read();
    for(int i=1;i<=n;++i){
        b[i]=read();
        if(b[i]==1){
            ++c[(i+n-2)%n+1];
            ++c[i];
            ++c[(i%n)+1];
        }
    }
    sort(c+1,c+1+n);
    reverse(c+1,c+1+n);
    int tot=0;
    for(int i=1;i<=a;++i) tot+=c[i];
    tot+=3*(n-a);
    printf("%d\n",tot);
    return 0;
}