#include<bits/stdc++.h>
using namespace std;
double v[60];
int main()
{
	int n;
	cin >> n;
	for (int i = 0;i < n;i++)
	{
		cin >> v[i];
	}
	sort(v,v + n);
	for (int i = 1;i < n;i++)
	{
		v[i] = (v[i - 1] + v[i]) / 2;
	}
	printf("%.6f\n",v[n - 1]);
	return 0;
}
