#include <bits/stdc++.h>
#define endl "\n"
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using ll = long long;
const int INF = 0x3f3f3f3f;
using namespace std;

int n;
double arr[51];
int main() {
    IOS
    cin >> n;
    for (int i = 0; i < n; ++i) {
        cin >> arr[i];
    }
    
    sort(arr, arr+n);
    for (int i = 1; i < n; ++i) {
        arr[i] = (arr[i]+arr[i-1])/2;
    }
    cout.presicion(5);
    cout << fixed << arr[n-1] << endl;

    return 0;


}
