#include<bits/stdc++.h>
#include<cstdio>
#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
const int maxn=10001;
int n,k;
int line[maxn];
double ans,t;
int l,r=-1,mid;
bool check(int x){
	int num=0;
	for(int i=1;i<=n;i++){
		num=num+line[i]/x;
	}
	//cout<<num<<endl;
	if(num>=k)return true;
	else return false;
}
int main(){
	freopen("cable.in","r",stdin);
	freopen("cable.out","w",stdout);
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;i++){
		scanf("%lf",&t);
		t*=100;
		line[i]=t;
		r=max(r,line[i]);
	}
	while(r-l>1){
		//cout<<l<<" "<<r<<endl;
		mid=(l+r)/2;
		if(check(mid))l=mid;
		else r=mid;
	}
	if(check(r))ans=r;
	else ans=l;
	ans/=100;
	printf("%.2f\n",ans);
	return 0;
}