#include <bits/stdc++.h>
using namespace std;
#define MAX 1010101
#define PI 3.1415926535897943383
int X[MAX];
typedef long double ld;
signed main() {
    ios::sync_with_stdio(false), cin.tie(0);
    cout<<fixed;
    cout.precision(20);
    int N;
    cin>>N;
    int i;
    int mx = 0;
    for(i=1;i<=N;i++) cin>>X[i],mx = max(mx, X[i]);
    sort(X+1, X+N+1);
    ld t=0;
    for(i=1;i<N;i++) {
        t += asin((ld)X[i]/((ld)X[N]));
    }
    ld l, r;
    l = mx;
    if(t>PI/2.0) {
        l = X[N];
        l*=0.5;
        r= 1e8;
        int T = 5000;
        while(T--){
            ld m = l+r;
            m/=2.0;
            //cout<<l<<' '<<r<<'\n';
            ld t=0;
            for(i=1;i<=N;i++) {
                t += asin(X[i]/(2*m));
            }
            if(t<PI) r=m;
            else l=m;
        }
    }
    else{
        l = X[N];
        l*=0.5;
        r= 1e8;
        int T = 5000;
        while(T--){
            ld m = l+r;
            m/=2.0;
            //cout<<l<<' '<<r<<'\n';
            ld t=0;
            for(i=1;i<N;i++) {
                t += asin(X[i]/(2*m));
            }
            if(t<asin(X[N]/(2*m))) l=m;
            else r=m;
        }
    }
    cout<<l;
}