#include<bits/stdc++.h>
using namespace std;
const int N=2e5+99;
#define double long double
const double eps=1e-10;
int n,k,a[N];
double s[N];
int p[N],pos[N];
bool cmp(int A,int B){
	if(fabs(s[A]-s[B])<=eps) return A<B;
	return s[A]<s[B];
}
int bit[N]; 
int query(int x){
	int re=0;
	while(x){
		re=max(re,bit[x]);
		x-=(x&(-x));
	}
	return re;
}
void add(int x,int val){
	while(x<N){
		bit[x]=max(bit[x],val);
		x+=(x&(-x));
	}
	return;
}
bool judge(double mid){
	for(int i=1;i<=n;i++)
		s[i]=s[i-1]+(double)a[i]-mid;
	for(int i=1;i<=n;i++) p[i]=i;
	sort(p+1,p+n+1,cmp);
	for(int i=1;i<=n;i++) pos[p[i]]=i;
	memset(bit,0,sizeof(bit));
	int now;
	if(s[n]<0) return false;
	for(int i=1;i<=n-1;i++){
		if(s[i]<0) continue;
		now=query(pos[i])+1;
		add(i,now);
	}
	now=query(pos[n])+1;
	return now>=k;
}
int main(){
	std::ios::sync_with_stdio(false);
	cin.tie(0);
	cin>>n>>k;
	for(int i=1;i<=n;i++)
		cin>>a[i];
	double l=0,r=1000,mid,ans;
	while(r-l>eps){
		mid=(l+r)/2;
		if(judge(mid)) ans=mid,l=mid;
		else r=mid;
	}
	cout<<fixed<<setprecision(8)<<ans;
	return 0;
}