#include<bits/stdc++.h>
using namespace std;
int main(){
  int N;
  double v[N];
  cin >> N;
  for(int i=0;i<N;i++) cin >> v[i];
  qsort(v, N, sizeof *v, [](const double* a, const double* b)
  {
    if(a < b) return -1;
    if(a > b) return 1;
    return 0;
  });
    
  double ans = v[0];
  for(int i=1;i<N;i++) ans = (ans+v[i])/2.0;
  cout << ans <<endl;
}