#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  vector<int> num(n);
  double ans = 0;
  for (auto &x : num) cin >> x;
  sort(num.begin(), num.end());
  for (int i = 1; i < n; i++) ans += num[i];
  ans /= (n - 1);
  cout << (num[0] + ans) / 2 << "\n";
  return 0;
}
