int main() {
    int n; cin >> n;
    vector<int> v(n);
    rep(i,n) cin >> v[i];
    sort(v.begin(), v.end());
    double ans = v[0];
    for (int i = 1; i < n; i++) ans += (double) (ans+v[i])/2;
    cout << setprecision(12) << ans << endl;
    return 0;
}