    temp = x[i];
    x[i] = x[j];
   x[j]=temp;
}

void QSort(double d[],int n){
  for(int i=0;i<n-1;i++){
    if(d[i]>d[i+1]){
      Swap(d,i,i+1);
    }
  }
}
       


int main(){
  int n;
  double count=0.0;
  scanf("%d",&n);
  double d[n];
  for(int i=0;i<n;i++){
    scanf("%lf",&d[i]);
  }
  QSort(d,n); 
  for(int i=0;i<n;i++){
    d[i+1]=(d[i]+d[i+1])/2;
  }
  printf("%lf",d[n-1]);
}
  