#include<cmath>
#include<cstdio>
typedef double real;
const int maxn=1005;
const real eps=1e-12,PI=acos(-1);
int n,a[maxn],max;
bool check(int f,real r){
	real sum=0;
	for(int i=1;i<=n;i++)sum+=asin(a[i]/(r*2));
	if(f==1)return sum-PI>-eps;
	else return 2*asin(max/(r*2))-sum>-eps;
}
real bs(int f,real l,real r){
	real m;
	while(r-l>eps){
		m=(l+r)/2;
		if(check(f,m))l=m;
		else r=m;
	}
	return check(f,l)?l:1e10;
}
real min(real a,real b){
	return a<b?a:b;
}
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		scanf("%d",a+i);
		if(max<a[i])max=a[i];
	}
	printf("%.10lf\n",min(bs(1,max/2.0,1e10),bs(2,max/2.0,1e10)));
	return 0;
}