import java.io.*;
import java.util.*;

class Main{
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		if(n == 1) {
		    System.out.println(sc.nextInt());
		}
		else {
		    int[] a = new int[n];
		    for(int i=0;i<n;i++) a[i] = sc.nextInt();
		    Arrays.sort(a);
		    double cur = (a[0]+a[1]) / 2.0;
		    for(int i=2;i<n;i++) {
		        cur = (cur + a[i]) / 2.0;
		    }
		    System.out.println(cur);
		}
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz