#include <bits/stdc++.h>
int main() {
  int a, count;
  int buf[50];
  scanf("%d", &count);
  for (int i = 0; i < count; i++) {
    scanf("%d", &buf[i]);
  }
  double tmp = 0;
  for (int i = 0; i < count; ++i) {
    for (int j = i + 1; j < count; ++j) {
      if (buf[i] < buf[j]) {
        tmp = buf[i];
        buf[i] = buf[j];
        buf[j] = tmp;
      }
    }
  }
  for (int i = 0; i < count; i++) {
    printf("%d", buf[i]);
  }
  for (int i = count - 1; i >= 0; i--) {
    buf[i - 1] = (buf[i - 1] + buf[i]) / 2;
  }
  printf("%lf", (double)buf[0]);
  return 0;
}
