#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  int mx = 0;
  double all = 0;
  cin >> n;
  vector<int> v(n + 1);
  for (int i = 1; i <= (n); i++) {
    cin >> v[i];
    all += v[i];
    mx = max(mx, v[i]);
  }
  if (n % 2 != 0) {
    all -= mx;
    all /= n - 1;
    all = (double)(all + mx) / 2;
    cout << fixed;
    cout << setprecision(6) << all << endl;
  } else {
    cout << fixed;
    cout << setprecision(6) << all / n << endl;
  }
  return 0;
}
