#include<bits/stdc++.h>
using namespace std;
#define IOS {cin.tie(0);cout.tie(0);ios::sync_with_stdio(0);}
#define rep(i,j,k) for(int i=j;i<=k;++i)
#define per(i,j,k) for(int i=j;i>=k;--i)
#define ll long long
#define vi vector<int>
#define db double
const int N=1e5+5;
int b[N],q[N];
signed main(){
    IOS
    int n,a;cin>>n>>a;
    rep(i,0,n-1)cin>>b[i];
    rep(i,0,n-1){
        rep(j,-1,1){
            int x=(i+j+n)%n;
            if(b[x]==0)++q[i];
        }
    }
    sort(q,q+n);
    int ans=n*3;
    rep(i,0,a-1)ans-=q[i];
    cout<<ans<<'\n';
}