import java.util.*;

class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		PriorityQueue<Double> pq = new PriorityQueue<>();
		for(int i = 0; i < n; i++){
			pq.add(sc.nextDouble());
		}
		//System.out.println(pq.poll());
		//double sum = 0;
		double a,b,x;
		while(pq.size() != 1){
			a = pq.poll();
			b = pq.poll();
			x = (a + b) / 2;
			pq.add(x);
	}
		double ans = pq.peek();
	System.out.println(ans);
	}
	
	
	}
/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