#include <bits/stdc++.h>
#include <numeric>
using namespace std;
#define ll long long
#define mod 100000007
#define rep(i, n) for (int i = 0; i < n; ++i)
using Graph = vector<vector<int>>;
#define grepq  priority_queue<double, std::vector<double>, std::greater<double>>

    int lcm(ll a, ll b)
{
    return a * b / __gcd(a, b);
}

const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

int main()
{
    int N;
    cin >> N;
    grepq pque;
    for (int i = 0; i < N; i++)
    {
        int a;
        cin >> a;
        pque.push(a);
    }
    double ans = 0;
    while(pque.size() != 1)
    {
        int b, c;
        b = pque.top();
        pque.pop();
        c = pque.top();
        pque.pop();
        pque.push((double)(b + c) / 2);
    }
    cout << pque.top() << endl;
}
