#include<bits/stdc++.h>
#define int long long
#define For(i,j,k) for(int i=(j);i<=(k);i++)
#define foR(i,j,k) for(int i=(j);i>=(k);i--) 
#define vi vector<int>
#define pb push_back
#define pii pair<int,int> 
#define mkp make_pair
#define SZ(x) ((int)x.size())
using namespace std;
inline int read() {
	char c;int res=0;bool flag=0;
	while(c=getchar(),c<48)(c=='-')&&(flag=1);
	do res=(res<<3)+(res<<1)+(c^48);
	while(c=getchar(),c>47);
	flag&&(res=-res); return res; 
}
int n;
double a[1003];
double eps=1e-10,pi=acos(-1);
bool deal(double x){
	double z=0;
	for(int i=1;i<=n;++i){
		z+=asin(a[i]/x);
	}
	if(z<pi)return 1;
	return 0;
}
bool deal1(double x){
	double z=-asin(a[1]/x);
	for(int i=2;i<=n;++i){
		z+=asin(a[i]/x);
	}
	if(z<0)return 0;
	return 1;
}
signed main(){
	n=read();
	for(int i=1;i<=n;++i){
		a[i]=read();
		a[i]/=2.0;
		if(a[i]>a[1])swap(a[1],a[i]);
	}
	double l=a[1],r=1e9,mid;
	if(deal(a[1])){
		int tim=1000;
		while(tim--){
			mid=(l+r)/2.0;
			if(deal1(mid))r=mid;
			else l=mid;
		}
	}
	else{
		int tim=1000;
		while(tim--){
			mid=(l+r)/2.0;
			if(deal(mid))r=mid;
			else l=mid;
		}
	}
	printf("%.10lf",l);
}