#include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
int n,k;
double a[100010];	
int check(int x)
{
	int ans=0;
	for(int i=1;i<=n;++i)
	    ans+=a[i]/x;
	return ans>=k;
}	
int main()
{
	cin>>n>>k;
	for(int i=1;i<=n;++i)
	{
		cin>>a[i];
		a[i]*=100;
	}   
	sort(a+1,a+n+1);
	double L=0,R=100000000,mid;
	while(L<R)
	{
		mid=(L+R+1)/2;
		if(check(mid))  L=mid;
		else            R=mid-1;
	}
	L/=100;
	printf("%.2lf\n",L);
	return 0;
}