#include <stdio.h>
#include <iostream>

#include <bits/stdc++.h>


using namespace std;

#define INPUT_INT(valName) int valName; cin >> valName;
#define INPUT_STR(valName) string valName; cin >> valName;
#define INPUT_LINE(valName) string valName; getline(cin,s);
#define INPUT_VECTOR_INT(valName, N) vector<int> valName(N); for(int i=0; i < N; ++i) { cin >> valName[i]; }
#define INPUT_VECTOR_DOUBLE(valName, N) vector<double> valName(N); for(int i=0; i < N; ++i) { cin >> valName[i]; }

#define OUTPUT(A) cout << (A) << endl;
#define OUTPUT2(A, B) cout << (A) << " " << (B) << endl;
#define OUTPUT3(A, B, C) cout << (A) << " " << (B) << " " << (C) << endl;

#define REP(valName, N) for(int valName = 0; valName < N; ++valName)

vector<string> split(const string &str, char delimiter) {
	vector<string> ret;
	string tmp = "";
	for (auto c : str) {
		if (c != delimiter) {
			tmp.push_back(c);
		} else {
			ret.push_back(tmp);
			tmp = "";
		}
	}
	ret.push_back(tmp);
	return ret;
}

template <typename T> void sortAsc(vector<T>& v) { sort(v.begin(), v.end(), less<T>()); }
template <typename T> void sortDesc(vector<T>& v) { sort(v.begin(), v.end(), greater<T>()); }


int main() {

	INPUT_INT(N);
	INPUT_VECTOR_DOUBLE(v, N);

	sortDesc(v);
	while (v.size() > 1) {
		v[0] = (v[0] + v[1]) / 2.0;
		v.erase(v.begin+1);
	}

	OUTPUT(v[0]);

	return 0;
}