#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
typedef long long ll;
using namespace std;

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