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

class Main{
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int N=sc.nextInt();
		double[] p=new double[N];
		for(int i=0; i<N; i++) {
			p[i]=sc.nextDouble();
		}
		Arrays.sort(p);
		double ans = 0d;
		ans=p[0];
		for(int i=1; i<N; i++) {
			ans=(ans+p[i])/2.0;
		}
		p(ans);
	}
	public static void p(Object o) {
		System.out.println(o);
	}
}
/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