import java.util.*;

public class Main {
	
	public static void main(String[] args)  {
		Scanner scan = new Scanner(System.in);
		
		int n=Integer.parseInt(scan.next());
		double[]v=new double [n];
		for (int i=0;i<n;++i) {
			v[i]=Double.parseDouble(scan.next());
		}
		Arrays.parallelSort(v);
		
		double sum=0;
		for(int i=0;i<n;++i) {
			if (i==0) {
				sum+=(v[i]+v[i+1])/2;
				
			}else if (i==1)continue;
			
			else {
				sum=(sum+v[i])/2;
			}
			
		}
		
		System.out.print(sum);
}
}
//end
/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