#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <string>
#include <chrono>
#include <random>

using namespace std;

#define sqr(x) x * x
#define all(x) x.begin(), x.end()
const int INF = 1e9;
const int MOD = 1e9 + 7;
typedef long long ll;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

void solve() {
	long long n;
	cin >> n;
	set<long double> q;
	for (long long i = 0; i < n; ++i) {
		long long x;
		cin >> x;
		q.insert(long double(x));
	}
	while (q.size() != 1) {
		long double tmp = *q.begin() + *next(q.begin());
		q.erase(q.begin());
		q.erase(q.begin());
		tmp /= 2;
		q.insert(tmp);
	}
	cout << *q.begin();
}

int main() {
#ifdef LOCAL
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
	int t = 1;
	//cin >> t;
	while (t--) {
		solve();
	}
	return 0;
}