1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 #include <cmath>
 5 using namespace std;
 6 
 7 int a[105], n;
 8 
 9 bool cmp(const int & a, const int & b)
10 {
11     return a > b;
12 }
13 
14 int main()
15 {
16     cin >> n;
17     for (int i = 0; i < n; i++)
18     {
19         cin >> a[i];
20     }
21     sort(a, a + n, cmp);
22     double res = a[0];
23     for (int i = 0; i < n - 1; i++)
24     {
25         res = 2.0 * sqrt(res * a[i + 1]);
26     }
27     printf("%.3f\n", res);
28     return 0;
29 }