#include <iostream>
#include <set>
using namespace std;

int main() {
  int n;
  cin >> n;
  set<double> st;
  for (int i = 0; i < n; ++i) {
    int tmp;
    cin >> tmp;
    st.insert(tmp);
  }
  set<double>::iterator it = st.begin();
  for (int i = 0, mid = (st.size() + 1) / 2 -1; i < mid; ++i) {
    ++it;
  }
  double res = *it;
  if (st.size() % 2 == 0) {
    ++it;
    res += *it;
    res /= 2.0;
  } 
    cout << res << endl;
    return 0;
}