#include <iostream>
#include <algorithm>
using namespace std;

int main(){
    int n;
    cin >> n;
    float* v = new float[n];
    for(int i=0;i<n;i++){
        cin >> v[i];
    } 
    sort(v,v+n);
    float ans=v[0];
    for(int i=1;i<n;i++){
        ans=(ans+v[i])/2;
    }   
    cout >> ans;
    return 0;
}