import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        int a[]=new int[n];
        for(int i=0;i<n;i++){
            a[i]=sc.nextInt();
        }
        Arrays.sort(a);
        double ans=a[0];
        for(int i=1;i<n;i++){
            ans+=a[i];
            ans/=2;
        }
        
        System.out.println(ans);
    }
}
