
import java.util.Arrays;
import java.util.Scanner;


public class Main {
	
	

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