#include <bits/stdc++.h>

using namespace std;

using ll = long long;

int main() {
    int N;
    cin >> N;
    std::vector<int> v(N);
    std::for_each(v.begin(), v.end(), [](auto &x) { cin >> x; });

    std::sort(v.begin(), v.end());

    std::vector<ll> pow_gain(N + 1);
    pow_gain[1] = 1;
    for (int i = 2; i < N; ++i) {
        pow_gain[i] = pow_gain[i - 1] * 2;
        v[i] = pow_gain[i] * v[i];
    }

    const double ans = static_cast<double>(std::accumulate(v.begin(), v.end(), 0)) / std::pow(2, N - 1);

    std::cout << std::fixed << std::setprecision(10) << ans << endl;
    
    return 0;
}
