#include<stdio.h>
int temp[50];
void mergesort(int v[],int left,int right)
{
  int mid,i,j,k;
  if(left>=right)
    return;
  mid=(left+right)/2;
  mergesort(v,left,mid);
  mergesort(v,mid+1,right);
  for(i=left;i<=mid;i++)
    temp[i]=v[i];
  for(i=mid+1,j=right;i<=right;i++,j--)
    temp[i]=v[j];
  i=left;
  j=right;
  for(k=left;k<=right;k++)
  {
    if(temp[i]<=temp[j])
      v[k]=temp[i++];
    else
      v[k]=temp[j--];
  }
int main()
  int N,i;
  scanf("%d",&N);
  double v[N];
  for(i=0;i<N;i++)
  {
    scanf("%lf",&v[i]);
  }
  mergesort(v,0,N-1);
  for(i=0;i<N-1;i++)
  {
    v[i+1]=(v[i]+v[i+1])/2;
  }
  printf("%lf",v[N-1]);
}