#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 10;
int dx[5] = {0, 0, 1, -1, 0}, dy[5] = {1, -1, 0, 0, 0};
const double EPS = 1e-10;
bool cmp(pair<int, int> a, pair<int, int> b) { return a.second < b.second; }
long long MOD = 1e9 + 7;
int n;
double v[60];
double ans;
int main(void) {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> v[i];
  double sum = 0.0;
  if (n % 2 == 0) {
    for (int i = 0; i < n; i++) sum += v[i];
    printf("%.8f\n", sum / n);
  } else {
    sort(v, v + n);
    for (int i = 0; i < n - 1; i++) sum += v[i];
    printf("%.8f\n", (sum / (2 * (n - 1))) + (v[n - 1] / 2));
  }
  return 0;
}
