#include <bits/stdc++.h>
int main() {
  int n;
  scanf("%d", &n);
  int i, ingrediente[n];
  for (i = 0; i < n; i++) {
    scanf("%d", &ingrediente[i]);
  }
  int frag = 0, j;
  for (j = 0; j < n && frag == 0; j++) {
    frag = 1;
    for (i = 0; i < n - j - 1; i++) {
      if (ingrediente[i] > ingrediente[i + 1]) {
        frag = 0;
        int aux = ingrediente[i];
        ingrediente[i] = ingrediente[i + 1];
        ingrediente[i + 1] = aux;
      }
    }
  }
  double media = ingrediente[0];
  for (i = 0; i < n - 1; i++) {
    media += ingrediente[i + 1];
    media = media / 2;
  }
  printf("%.1lf\n", media);
  return 0;
}
