#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;

int main() {
  int N; cin >> N;
  vector<int> S(N);
  for(int i = 0; i < N; i++){
    cin >> S[i];
  }
  sort(S.begin(), S.end());
  double ans;
  if(N%2 != 0){
    ans = (double)S[N/2];
  }else{
    ans = (S[N/2-1] + S[N/2])/2.0;
  }
  cout << fixed << setprecision(5);
  cout << ans << endl;
}