import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		
		List<Double>values= new ArrayList<>();
		for(int i=1;i<=N;i++) {
			values.add(sc.nextDouble());
		}
		Collections.sort(values);
		for(int j=1;j<N;j++) {
			double newvalue=(values.get(0)+values.get(1))/2.0;
			values.remove(0);
			values.remove(0);
			values.add(newvalue);
			Collections.sort(values);
		}
		System.out.println(values.get(0));
	}
}	
/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