#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#define REP(i,n) for(int i=0;i<(n);++i)
#define SORT(a) sort((a).begin(),(a).end())
#define PB push_back
using namespace std;
typedef vector<int> VI;

int main(){
  int N;
  cin >> N;
  VI v;
  REP(i,N){
    int A;
    cin >> A;
    v.PB(A);
  }
  SORT(v);
  double r = v[(N - 1) / 2] + v[N / 2];
  cout << r / 2 << endl;
}