#include <bits/stdc++.h>
using namespace std;
#define FOR(i, x, n) for(ll i = x; i < n; i++) 
#define pb push_back
#define ll long long
#define hii cout << "hii" << endl
#define pii pair<int, int>
#define pll pair<ll, ll>
#define int ll
#define mpp make_pair
#define endl '\n'
#define ff first 
#define ss second
#define all(s) s.begin(), s.end()
#define fuck_you_scanf ios_base:: sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define si size()
 
const int N = 1e6 + 5;
bool visited[N];

int32_t main()
{
    int n;
    cin >> n;
    multiset<long double> m;
    for(int i = 0; i < n; i++)
    {
        long double data;
        cin >> data;
        m.insert(data);
    }
    int t = n - 1;
    while(t--)
    {
        auto it1 = m.begin();
        auto it2 = it1;
        it2++;
        int a = *it1;
        int b = *it2;
        m.erase(it1);
        m.erase(it2);
        m.insert(((a + b) * 1.0) / 2.0);
    }
    std::cout << std::setprecision(5) << *m.begin(); << '\n';
}