#include <algorithm>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

using namespace std;

typedef long long ll;

#define MOD 1000000007

int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
  }
  sort(a.begin(), a.end());
  if (n & 1) {
    cout << a[n / 2] << endl;
  } else {
    double ans = (1.0 * a[n / 2 - 1] + 1.0 * a[n / 2]) / 2.0;
    printf("%.5f\n", ans);
  }
  return 0;
}