#include <bits/stdc++.h>

using namespace std;

int n;
double v[51];

int main()
{
	cin >> n;
	for (int i = 0; i < n; ++i)
	{
		cin >> v[i];
	}
	sort(v, v + n);
	double ans = v[0];
	for (int i = 1; i < n; ++i)
	{
		ans = (ans + v[i]) / 2;
	}
	cout << ans << endl;
}