#include<bits/stdc++.h>
using namespace std;
const int Max_N=1e3;
int n,L[Max_N+5];
bool chck(long double x){
	long double sum=0;
	for(int i=1;i<n;i++)
	 sum+=acos(1.0-(1.0*L[i]*L[i])/(2.0*x*x));
	return sum>=acos(1.0-(1.0*L[n]*L[n])/(2.0*x*x));
}
bool CHCK(long double x){
	long double sum=0;
	for(int i=1;i<=n;i++)
	 sum+=acos(1.0-(1.0*L[i]*L[i])/(2.0*x*x));
	return sum<=2*acos(-1.0);
}
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++) scanf("%d",&L[i]);
	sort(L+1,L+n+1);
	long double l=0,r=1e9;
	for(;fabs(r-l)>=(1e-8);){
		long double mid=(l+r)/2;
		if(chck(mid)) r=mid;
		else l=mid;
	}
	if(chck(r)){
		printf("%.8Lf\n",r);
		return 0;
	}
	l=0,r=1e9;
	for(;fabs(r-l)>=(1e-8);){
		long double mid=(l+r)/2;
		if(CHCK(mid)) r=mid;
		else l=mid;
	}
	printf("%.8Lf\n",l);
	return 0;
}