#include<bits/stdc++.h>
using namespace std;
#define double long double
const double pi=acos(-1.);
int n;
int a[23333];
double cal(double R)
{
	double turn=0.;
	for(int i=1;i<=n;i++)
	{
		turn+=acos((2.*R*R-a[i]*a[i])/(2.*R*R));
	}
	return turn;
}
double cal2(double R)
{
	double turn=0.;
	for(int i=1;i<n;i++)
	{
		turn+=acos((2.*R*R-a[i]*a[i])/(2.*R*R));
	}
	turn-=acos((2.*R*R-a[n]*a[n])/(2.*R*R));
	return turn;
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin>>n;
	double sum=0,maxx=0;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
		sum+=a[i];
		maxx=max(maxx,(double)a[i]);
	}
	sort(a+1,a+n+1);
//	for(int i=50;i<=50000;i++)cerr<<i<<' '<<cal2(i)<<endl;
	double l=maxx/2+1e-8,r=sum;
	for(int tt=1;tt<=200;tt++)
	{
		double mid=(l+r)/2;
		double turn=cal(mid);
		if(turn<pi*2)r=mid;
		else l=mid;
	}
	if(l<=maxx/2+1e-8)
	{
		l=maxx/2+1e-8,r=3e5;
		for(int tt=1;tt<=200;tt++)
		{
			double mid=(l+r)/2.;
			double turn=cal2(mid);
//			cerr<<l<<' '<<r<<' '<<turn<<endl;
			if(turn<0)l=mid;
			else r=mid;
		}
	}
	cout<<fixed<<setprecision(12)<<l<<endl;
	return 0;
}