#include<bits/stdc++.h>
using namespace std;
int a[1005];
double x[1005];
const double pi=acos(-1);
int main(){
	int n;
	cin>>n;
	for(int i=1;i<=n;++i)scanf("%d",&a[i]);
	double l1=0,r1=1e7;
	while(r1-l1>1e-8){
		double mid=(l1+r1)/2,he=0;
		for(int i=1;i<=n;++i){
			x[i]=acos(1-1/2.0*a[i]*a[i]/mid/mid);
			he+=x[i];
		}
		if(he<2*pi)r1=mid;
		else l1=mid;
	}
	double l2=0,r2=1e7;
	while(r2-l2>1e-8){
		double mid=(l2+r2)/2,he=0,mx=0;
		for(int i=1;i<=n;++i){
			x[i]=acos(1-1/2.0*a[i]*a[i]/mid/mid);
			he+=x[i],mx=max(mx,x[i]);
		}
		if(he<2*mx)r2=mid;
		else l2=mid;
	}
	printf("%.8f\n",min(l1,l2));
	return 0;
}