#include <bits/stdc++.h>

using namespace std;

#define MAXN 200010

long long n,k;
long long a[MAXN];
double b[MAXN],pref[MAXN];
map<double,long long> mapa;
long long seg[MAXN*4];
vector<long long> vec;

void update(long long node,long long l,long long r,long long pos,long long val)
{
    if (l==r) seg[node]=val;
    else
    {
        long long mid=(l+r)/2;
        if (pos<=mid) update(2*node,l,mid,pos,val);
        else update(2*node+1,mid+1,r,pos,val);
        seg[node]=max(seg[2*node],seg[2*node+1]);
    }
}

long long query(long long node,long long l,long long r,long long a,long long b)
{
    if (a>b) return 0;
    if (l==a and r==b) return seg[node];
    long long mid=(l+r)/2;
    return max(query(2*node,l,mid,a,min(b,mid)),query(2*node+1,mid+1,r,max(a,mid+1),b));
}

bool check(double t)
{
    //cout<<t<<endl;
    for (long long i=1;i<=n;i++) b[i]=(double)(a[i])-t;
    /*for (long long i=1;i<=n;i++) cout<<b[i]<<" ";
    cout<<endl;*/
    pref[0]=0;
    for (long long i=1;i<=n;i++) pref[i]=pref[i-1]+b[i];
    /*for (long long i=1;i<=n;i++) cout<<pref[i]<<" ";
    cout<<endl;*/
    for (long long i=1;i<=n;i++) mapa[pref[i]]=1;
    long long pret=1;
    for (auto&p:mapa) {p.second=pret;pret++;}
    vec.push_back(0);
    for (long long i=1;i<=n;i++)
    {
        if (pref[i]<0) continue;
        vec.push_back(mapa[pref[i]]);
    }
    long long siz=vec.size()-1;
    /*for (long long i=1;i<=siz;i++) cout<<vec[i]<<" ";
    cout<<endl;*/
    mapa.clear();
    for (long long i=1;i<=4*n;i++) seg[i]=0;
    long long br;
    for (long long i=1;i<=siz;i++)
    {
        long long lis=query(1,1,n,1,vec[i])+1;
        update(1,1,n,vec[i],lis);
        if (i==siz) br=lis;
    }
    vec.clear();
    if (br>=k) return true;
    else return false;
}

int main()
{
    ios_base::sync_with_stdio(false);
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    cin>>n>>k;
    for (long long i=1;i<=n;i++) cin>>a[i];
    long long sum=0;
    for (long long i=1;i<=n;i++) sum+=a[i];
    double sredina=sum*1.00/n;
    double l=0,r=sredina;
    double rez=0;
    while (r-l>=0.00001)
    {
        double mid=(l+r)/2;
        if (check(mid)) {rez=mid;l=mid;}
        else r=mid;
    }
    cout<<fixed<<showpoint<<setprecision(5)<<rez<<endl;
}