#include<bits/stdc++.h>
#define db double
#define MAX 1005
using namespace std;
const double eps=1e-8;
const double pi=acos(-1);
const long long inf=1e8;
int n;
db a[MAX],b[MAX],ans,ret1,ret2;
bool check(double x,int type){
	double ret=0,tx=2*x*x;
	for(int i=1;i<=n-1;i++)
		ret+=acos((tx-b[i])/(tx));
	if(type==1) ret+=acos((tx-b[n])/tx);
	else ret+=2*pi-acos((tx-b[n])/tx);
//	if(type==2) printf("%.8lf %.8lf %.8lf\n",x,ret,2*pi);
//	if(x==94723.6448403) cout<<ret<<endl;
	if(abs(ret-2*pi)<=1e-4) type==1?ret1=x:ret2=x;
	if(type==1){
		if(ret<=2*pi) return 1;
		return 0;
	}else{
		if(ret-2*pi>=1e-6) return 0;
		return 1;
	}
}
double ck(int type){
	double l=a[n]/2,r;
	r=inf;
	type==1?ret1=inf:ret2=inf;
	while(l<r-eps){
		double mid=(l+r)/2;
		if(check(mid,type)) type==1?r=mid:l=mid;
		else type==1?l=mid:r=mid;
	}
	return type==1?ret1:ret2;
}
int main(){
//	freopen("1.in","r",stdin);
	scanf("%d",&n);
	for(int i=1;i<=n;i++) scanf("%lf",&a[i]);
	sort(a+1,a+1+n);
	for(int i=1;i<=n;i++) b[i]=a[i]*a[i];
	ans=min(ck(1),ck(2));
	printf("%.8lf",ans);
}