#include <bits/stdc++.h>
using namespace std;
int N;
int store[55];
int main() {
  cin >> N;
  for (int i = 0; i < N; i++) scanf("%d", &store[i]);
  sort(store, store + N);
  double ans = store[0];
  for (int i = 1; i < N; i++) {
    ans = (ans + (double)store[i]) / 2.0;
  }
  printf("%.1f\n", ans);
}
