#include <bits/stdc++.h>
using namespace std;
const long long M = 1e9 + 7;
const double pi = 3.141592653589793238463;
long long modularExponentiation(long long x, long long n, long long M) {
  long long result = 1;
  while (n > 0) {
    if (n % 2 == 1) result = (result * x) % M;
    x = (x * x) % M;
    n = n / 2;
  }
  return result;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long n;
  cin >> n;
  long long a[n];
  for (long long i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  for (long long i = 0; i < n - 1; i++)
    a[i + 1] = (long double)((a[i] + a[i + 1]) / 2);
  cout << a[n - 1];
}
