#include <bits/stdc++.h>
using namespace std;
long long s = 0, n = 0, i = 0;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  cin >> n;
  double x = 0, y = 0;
  long long a[n];
  stack<long long> even;
  stack<long long> odd;
  for (i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] % 2 == 0) {
      even.push(a[i]);
    } else {
      odd.push(a[i]);
    }
  }
  x = -1;
  bool flag = 1;
  while (!even.empty() || !odd.empty()) {
    if (!odd.empty()) {
      x = odd.top();
      odd.pop();
    } else {
      x = even.top();
      even.pop();
    }
    if (flag == 1) {
      y = x;
      flag = 0;
    } else {
      y = (y + x) / 2;
    }
  }
  printf("%f", y);
  return 0;
}
