#include<bits/stdc++.h>
using namespace std;
int n,k;
double ans,s,a[10005];
bool check(double x)
{
	int sum=0;
	for(int i=1;i<=n;i++)
		sum+=a[i]/x;
	return sum>=k;
}
int main()
{
	cin>>n>>k;
	for(int i=1;i<=n;i++)
		cin>>a[i],s+=a[i];
	double left=0.0,right=s/k;
	while(left<=right)
	{
		double mid=(left+right)/2.0;
		if(mid==0.0)
			break;
		if(check(mid))
			left=mid+0.01,ans=mid;
		else
			right=mid-0.01;
	}
	printf("%.2lf",ans);
	return 0;
}