#include<algorithm>
#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
typedef long double ld;
const ld pi=acos(-1),eps=1e-10;
ld ans=1e18;
int n;
int a[1005];
bool check(ld r){
    ld res=0;
    int i;
    for(i=1;i<=n;i++){
        ld c=1-(a[i]*a[i])/(2*r*r);
        if(c<=-1)
            res+=pi;
        else
            res+=acos(c);
    }
    return res<=2*pi;
}
bool cmp(int a,int b){
    return a>b;
}
bool check2(ld r){
    ld res=0;
    int i;
    for(i=2;i<=n;i++){
        ld c=1-(a[i]*a[i])/(2*r*r);
        if(c<=-1)
            res+=pi;
        else
            res+=acos(c);
    }
    i=1;
    ld c=1-(a[i]*a[i])/(2*r*r);
    if(c<=-1)
        res-=pi;
    else
        res-=acos(c);
    return res>0;
}
int main(){
    int i;
    ld l=0,r=1e9,mid;
    scanf("%d",&n);
    for(i=1;i<=n;i++){
        scanf("%d",&a[i]);
    }
    sort(a+1,a+n+1,cmp);
    l=a[1]/2;
    while(r-l>eps){
        mid=(l+r)/2;
        if(check(mid))
            r=mid;
        else
            l=mid;
    }
    if(l>a[1]/2+eps)
        ans=l;
    
    l=a[1]/2;r=1e10;
    while(r-l>eps){
        mid=(l+r)/2;
        if(check2(mid))
            r=mid;
        else
            l=mid;
    }
    if(ans>1e17)
        ans=min(ans,l);
    printf("%.10Lf",ans);
    return 0;
}