#include <bits/stdc++.h>
using namespace std;

int main(){

    int N;
    cin >> N;

    vector<double> v(N);
    for (size_t i = 0; i < N; i++)
    {
        cin >> v[i];
    }
    sort(v.begin(),v.end());
    ans = v[0]; 
    for(int i=1;i<N;i++){
        ans= (ans+v[i])/2;
    }
    cout << ans << endl;

    return 0;
}