#include <iostream>
#include <cstdio>
#include <queue>
#include <math.h>
#include <cstring>
#include <algorithm>
using namespace std;

priority_queue<double> que;

int main()
{
    int n;
    scanf("%d", &n);
    
    for (int i = 0; i < n; i++) {
        double m;
        scanf("%lf", &m);
        que.push(m);
    }
    
    while (que.size() > 1) {
        double m1 = que.top();
        que.pop();
        double m2 = que.top();
        que.pop();
        que.push(2 * sqrt(m1 * m2));
    }
    
    printf("%.3f\n", que.top());
    
    return 0;
}