#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std; int main()
{
int n;
double w[105];
while(~scanf("%d",&n))
{
for(int i=0;i<n;i++)
{
int m;
scanf("%d",&m);
w[i]=m*1.0;
} sort(w,w+n);
for(int i=n-1;i>0;i--)
{
w[i-1]=2*sqrt(w[i]*w[i-1]);
}
printf("%.3lf\n",w[0]);
}
return 0;
}