#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N = 3e5 + 10;
int n, a[N], cnt = 0;
double ans = -1;
signed main() {
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> a[i];
	sort(a + 1, a + n + 1, greater<int>());
	for (int i = 1; i <= n; i++) {
		cnt += a[i];
		ans = max(ans, cnt * cnt * 1.0 / i * 1.0);
	}
	printf("%.8lf", ans);
	return 0;
}