#include <iostream>

#include <algorithm>

#include <iomanip>

#include <cmath>

#define MAXN 100

using namespace std;

double _m[MAXN];

double fun();

int n;

int main()

{

    //freopen("acm.acm","r",stdin);

    int i;

    cin>>n;

    for(i = ; i < n; ++ i)

    {

        cin>>_m[i];

    }

    double tem = fun();

    for(i = ; i < n; ++ i)

    {

        tem = *sqrt(fun()*tem);

    }

    cout<<setiosflags(ios::fixed)<<setprecision()<<tem<<endl;

}

double fun()

{

    int i;

    double max = -;

    int index;

    for(i = ; i < n; ++ i)

    {

        if(_m[i] > max)

        {

            max = _m[i];

            index = i;

        }

    }

    _m[index] = -;

    return max;

}