> #include<iostream>
> #include<math.h>
> #include<algorithm>
> using namespace std;
> #define MAX 101
> 
> double weight[MAX];
> int n;
> bool cmp(int a, int b) { return a > b; }
> 
> int main()
> {
> 	scanf("%d", &n);
> 	int i;
> 	for(i = 0; i < n; i ++) scanf("%lf", &weight[i]);
> 	
> 	for(i = 0; i < n - 1; i ++)
> 	{
> 		sort(weight + i, weight + n, cmp);
> 		weight[i + 1] = 2 * sqrt(double(weight[i] * weight[i + 1]));
> 	}
> 	printf("%.3lf\n", weight[n - 1]);
> }