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

int main()
{
  	int n;
    double ans;
    vector<double> v[n];
	cin >> n;
  
  	for(int i = 0; i < n; i++) cin >> v[i];
  	v.resize(n);
	sort(v.begin(), v.end());
  	ans = (v[0]+v[1])/2.0;
  	for(int i = 2; i < n; i++)
    {
      ans = (ans+v[i])/2.0;
    }
  	cout << ans << endl;
}
