import java.util.*;
import java.lang.*;

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