#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
template <class T>
struct rge {
  T b, e;
};
template <class T>
rge<T> range(T i, T j) {
  return rge<T>{i, j};
}
template <class T>
auto dud(T* x) -> decltype(cerr << *x, 0);
template <class T>
char dud(...);
struct debug {
  template <class T>
  debug& operator<<(const T&) {
    return *this;
  }
};
const ll MOD = (ll)1e9 + 7;
const ld PI = acos(-1);
template <class T>
T gcd(T x, T y) {
  return (y == 0) ? x : gcd(y, x % y);
}
template <class T>
void mini(T& a, T b) {
  a = min(a, b);
}
template <class T>
void maxi(T& a, T b) {
  a = max(a, b);
}
template <class T>
T mul(T x, T y) {
  return (x * y) % MOD;
}
template <class T>
inline T power(T a, T b) {
  T res = 1;
  while (b > 0) {
    if (b & 1) {
      res = mul(res, a);
    }
    a = mul(a, a);
    b >>= 1;
  }
  return res % MOD;
}
template <class T>
inline T modInverse(T n) {
  return power(n, MOD - 2, MOD) % MOD;
}
string to_string(string s) { return '"' + s + '"'; }
string to_string(char s) { return string(1, s); }
string to_string(const char* s) { return to_string((string)s); }
template <class T, class U>
string to_string(pair<T, U> p) {
  return to_string(p.first) + " " + to_string(p.second);
}
const int MX = (int)6e3 + 5;
int main(int argc, char** argv) {
  int n, m;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) cin >> a[i];
  sort(std::begin(a), std::end(a));
  ld sum = 0;
  for (int i : a) sum = (sum + i) / 2;
  cout << sum << endl;
  return 0;
}
