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);


		    sc.close();
	}
}
