import java.util.*;
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 ans=v[0];
		for(int i=1;i<n;i++){
			ans=(ans+v[i])/2;
		}
		System.out.println(ans);
			
	}
	
}