#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;
using ll = long long;
int main() {
    int N;
    double ans = 0;
    cin >> N;
    double v[N];
    for (int i = 0; i < N; ++i) {
        cin >> v[i];
    }
    sort(v.begin() , v.end());
    ans = v[0];
    for(int i = 1; i < N; i++){
        ans = (nas + v[i]) / 2;
    }
    cout << ans << endl;
}