#include <bits/stdc++.h>
using namespace std;
template <typename T>
using pq = priority_queue<T, vector<T>, greater<T>>;
using ll = long long;
ll INF = LLONG_MAX / 4 - 100;
ll mod = 1e9 + 7;
long long dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1};
vector<ll> prime;
class fact {
 public:
  long long fmod = 1e9 + 7;
  vector<long long> fac, inv;
  fact(long long n, long long Mod = 1e9 + 7) {
    fmod = Mod;
    fac = vector<long long>(n, 0);
    inv = vector<long long>(n, 0);
    fac[0] = 1;
    for (long long i = 1; i < n; i++) fac[i] = fac[i - 1] * i % fmod;
    for (long long i = 0; i < n; i++) inv[i] = fact::POW(fac[i], fmod - 2);
  }
  ll nCr(ll n, ll r) { return (fac[n] * inv[r] % fmod) * inv[n - r] % fmod; }
  ll POW(ll a, ll b) {
    ll c = 1;
    while (b > 0) {
      if (b & 1) {
        c = a * c % fmod;
      }
      a = a * a % fmod;
      b >>= 1;
    }
    return c;
  }
  inline long long operator[](long long i) { return fac[i]; }
};
template <class T = ll>
T in() {
  T x;
  cin >> x;
  return (x);
}
void DEBUG(vector<long long> a) {
  for (long long i = 0; i < a.size(); i++) cout << a[i] << " ";
  cout << endl;
}
void EMP(long long x) { cout << "!!!" << x << "!!!" << endl; }
ll GCD(ll a, ll b) {
  ll c;
  while (b != 0) {
    c = a % b;
    a = b;
    b = c;
  }
  return a;
}
ll LCM(ll a, ll b) { return (a / GCD(a, b)) * (b / GCD(a, b)) * GCD(a, b); }
ll POW(ll a, ll b) {
  ll c = 1;
  while (b > 0) {
    if (b & 1) {
      c = a * c % mod;
    }
    a = a * a % mod;
    b >>= 1;
  }
  return c;
}
void PRI(ll n) {
  bool a[n + 1LL];
  for (long long i = 0; i < n + 1LL; i++) {
    a[i] = 1LL;
  }
  for (long long i = 2; i < n + 1LL; i++) {
    if (a[i]) {
      prime.push_back(i);
      ll b = i;
      while (b <= n) {
        a[b] = 0;
        b += i;
      }
    }
  }
}
template <typename T>
T chmin(T& a, T b) {
  if (a > b) a = b;
  return a;
}
template <typename T>
T chmax(T& a, T b) {
  if (a < b) a = b;
  return b;
}
bool isSqrt(ll a) { return pow(sqrt(a), 2) == a ? 1 : 0; }
void YesNo(bool a) {
  if (a)
    cout << "Yes";
  else
    cout << "No";
  cout << endl;
}
void yesno(bool a) {
  if (a)
    cout << "yes";
  else
    cout << "no";
  cout << endl;
}
void YESNO(bool a) {
  if (a)
    cout << "YES";
  else
    cout << "NO";
  cout << endl;
}
double dis(long long x1, long long x2, long long y1, long long y2) {
  return sqrt((double)abs(x1 - x2) * (double)abs(x1 - x2) +
              (double)abs(y1 - y2) * (double)abs(y1 - y2));
}
bool solve() {
  long long n;
  cin >> n;
  double v[n];
  for (long long(i) = (0); (i) < (n); (i)++) cin >> v[i];
  vector<double> next;
  vector<double> now;
  sort(v, v + n);
  for (long long(i) = (0); (i) < (n); (i)++) now.push_back(v[i]);
  for (long long(i) = (0); (i) < (now.size()); (i)++) {
    if (now.size() == 1) break;
    double nx = now[0] + now[1];
    nx /= 2;
    next.clear();
    next.push_back(nx);
    for (long long(j) = (2); (j) < (now.size()); (j)++) {
      next.push_back(now[j]);
    }
    now = next;
    next.clear();
  }
  cout << now[0] << endl;
}
signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  solve();
}
