#include <bits/stdc++.h>
using namespace std;
int const N = 1e6 + 100;
long long int const LINF = numeric_limits<long long int>::max();
int const INF = numeric_limits<int>::max();
int const BN = 31;
long long int gcd(long long int a, long long int b) {
  return b ? gcd(b, a % b) : a;
}
long long int pow_mod(long long int a, long long int e, long long int m) {
  long long int res = 1;
  while (e) {
    if (e & 1) res = res * a % m;
    a = a * a % m;
    e >>= 1;
  }
  return res;
}
long long int inv_mod(long long int b, long long int m) {
  b %= m;
  long long int x = 0, y = 1, r, q, a = m;
  while (b) {
    q = a / b;
    r = a % b;
    a = b;
    b = r;
    r = x;
    x = y;
    y = r - q * y;
  }
  x += m;
  return x % m;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  vector<double> arr(n);
  for (int i = 0; i < n; i++) cin >> arr[i];
  sort(arr.begin(), arr.end());
  for (int i = n - 1; i > 0; i--) {
    arr[i - 1] = (arr[i] + arr[i - 1]) * 0.5;
  }
  cout << arr[0] << endl;
}
