#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  long long r;
  while (b > 0) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
long long powmod(long long a, long long b, long long mod) {
  long long res = 1;
  a %= mod;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
  }
  return res;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  long long n;
  double sum = 0;
  cin >> n;
  long long a[n + 1];
  for (int i = 1; i <= n; i++) cin >> a[i];
  sort(a + 1, a + n + 1);
  for (int i = 2; i <= n; i++) {
    sum = (a[i] + a[i - 1]) / 2;
    a[i] = sum;
  }
  cout << sum << '\n';
  return 0;
}
