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

int main(){
    int n;
	cin >> n;
	vector<int> input;
	for(int i=0; i<n; i++){
		double tmp;
		cin >> tmp;
		input.push_back(tmp);
	}
	sort(iput.begin(), input.end());
	
	double prev=input[0];
	double cur=input[1];
	int i=1;
	while(i<input.size()){
		cur = input[i];
		prev = (prev+cur)/2.0;
		i++;
	}
	cout << prev << endl;
	
    return 0;
}
