#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline void CHMAX(T& a, const T b) {
  if (a < b) a = b;
}
template <typename T>
inline void CHMIN(T& a, const T b) {
  if (a > b) a = b;
}
constexpr long long MOD = 1000000007ll;
const double EPS = 1e-11;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << setprecision(10) << fixed;
  int n;
  double v[55];
  cin >> n;
  for (int i = 0; i < (n); ++i) {
    cin >> v[i];
  }
  sort(v, v + n);
  double ans = 0;
  for (int i = 0; i < (n - 1); ++i) {
    ans += v[i];
  }
  ans /= n - 1;
  cout << (ans + v[n - 1]) / 2 << '\n';
  return 0;
}
