#include <algorithm>
#include <climits>
#include <cmath>
#include <csignal>
#include <cstdio>
#include <cstdlib>
#include <iomanip>
#include <iostream>
#include <queue>
#include <string>
#include <vector>

using ll = long long;
using namespace std;

int main() {
    int n = 0;
    cin >> n;
    vector<double> v(n);
    for (int i=0; i<n; i++) {
        cin >> v.at(i);
    }
    sort(v.begin(), v.end());
    double ans = a.at(0);
    for (int i=1; i<n; i++) {
        ans = (ans + v.at(i)) / 2;
    }
    cout << fixed;
    cout << setprecision(10) << ans << endl;
    return 0;
}
