#include <bits/stdc++.h>
using namespace std;
#define popcnt(a) __builtin_popcount(a)
#define FastIO() ios::sync_with_stdio(false), cin.tie(0);
#define IO() freopen("palindrome.in","rw",stdin)
#define error(args...)                       \
{                                            \
    cerr<<"LINE "<<__LINE__;                 \
    string _s = #args;                       \
    replace(_s.begin(), _s.end(), ',', ' '); \
    stringstream _ss(_s);                    \
    istream_iterator<string> _it(_ss);       \
    err(_it, args);                          \
    cerr<<endl;                              \
}
void err(istream_iterator<string> it)
{
} 
template <typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args)
{
  cerr<<' '<< *it << " = " << a ;
  err(++it, args...);
} 
typedef long long LL;
const LL MOD = 1e9 + 7;
const int N = 1e6+9, M = (1<<31), OO = 0x3f3f3f3f;
priority_queue<double,vector<double>,greater<double>>pq;

int main()
{
  int n;
  scanf("%d",&n);
  for(int i=0;i<n;++i)
  {
    double x;
    scanf("%lf",&x);
    pq.push(x);
  }
  double res =0;
  while(!pq.empty())
  {
    double x,y;
    x = pq.top();
    pq.pop();
    y = pq.top();
    pq.pop();
    res = (x+y)/2;
    if(pq.empty()) break;
    pq.push(res);
  }
  printf("%.5lf",res);
  #ifdef _LOCAL_DEFINE
  cerr << (double)clock() * 1.0 / CLOCKS_PER_SEC << endl;
  #endif
  return 0; 
}