#include <bits/stdc++.h>
using namespace std;

double a[300005];

bool cmp(int x, int y)
{
    return x > y;
}

int main()
{
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
    }
    long double meiwei = 0;
    long double maxn = 0;
    sort(a + 1, a + n + 1, cmp);
    for(int i = 1;i <= n;i ++)
    {
    	meiwei += a[i];
    	if(maxn <= meiwei * meiwei * 1.0 / i) 
    	{
    		maxn = meiwei * meiwei * 1.0 / i;
    	}
    }
    cout << maxn << endl;
    return 0;
}