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

int n;
double v[60],ans;

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