#include <bits/stdc++.h>
using namespace std;
int asc(const void *a, const void *b) { return *(int *)a - *(int *)b; }
int main() {
  int n, v[100];
  float result = 0;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%d", &v[i]);
  }
  qsort(v, n, sizeof(int), asc);
  for (int i = 0; i < n; i++) {
    result = (result + v[i]) / 2.0;
  }
  printf("%f\n", result);
  return 0;
}
