#include <iostream> 
using namespace std;
#include <cstdio>
#include <string>
#include <vector>
#include <queue>
#include <algorithm>
int main()
{
	
	int n;
	cin>>n;
	queue<double>r;
	vector<double>nex;
	double m = 0;
	for(int i = 0;i<n;i++)
	{
		cin>>m;
		nex.push_back(m);
	}
	
	sort(nex.begin(),nex.end());
	
	for(auto &x :nex)
	{
		r.push(x);
	}
	
	double sum = r.front();
	r.pop();
	while(r.size())
	{
		double sec= r.front();
		r.pop();
		sum = (sum+sec)/2;
	}
	
	cout<<sum<<endl;
	
	return 0;
}