#include <bits/stdc++.h>
using namespace std;
const int N = 100;
double a[N];
int main() {
  int n;
  cin >> n;
  for (long long i = 1; i <= n; ++i) cin >> a[i];
  for (long long k = 1; k <= n - 1; ++k) {
    int now = 0x3f3f3f3f;
    int q1, q2;
    for (long long i = 1; i <= n; ++i)
      for (long long j = 1; j <= n; ++j)
        if (i != j) {
          if (abs(a[i] - a[j]) < now) {
            now = abs(a[i] - a[j]);
            q1 = i;
            q2 = j;
          }
        }
    a[q1] = (a[q1] + a[q2]) / 2;
    a[q2] = 0x3f3f3f3f;
  }
  for (long long i = 1; i <= n; ++i)
    if (a[i] != 0x3f3f3f3f) return cout << a[i], 0;
}
