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