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 ans=v[0];
		for(int i=1;i<N;i++)ans=(ans+v[i])/2;
		System.out.println(ans);
	}
}