import java.util.*;
public class Main {
 public static void main(String[] args){
	Scanner sc = new Scanner(System.in);
	int N=sc.nextInt();
    int[] v=new int[N];
   	for(int i=0;i<N;i++)v[i]=sc.nextInt();
   	Arrays.sort(v);
    double r=v[0];
   	for(int i=1;i<N;i++)r=(r+v[i])/2;
	System.out.println(r);
 }
}
