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);

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

	}
}
