#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)

int main(void)
{
  int n;
  cin >> n;
  vector<int> a(n);
  rep(i, n) cin >> a.at(i);
  sort(a.begin(), a.end());
  if (n % 2 == 0)
  {
    double ans = (a.at(n /2) + a.at(n/2 - 1)) / 2.0;
    printf("%.2f\n", ans);
  }
  else
  {
    cout << a.at(n / 2) << endl;
  }
  return 0;
}