#include<bits/stdc++.h>
using namespace std;
int main()
{
  int n;
  int v[1005];
  double x=0;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>v[i];
  }
  sort(v,v+n);
  x=(double)v[0];
  for(int i=1;i<n;i++){
    x=(x+(double)v[i])/2;
  }
  cout<<x<<"\n";
  return 0;
}
