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

public class Main{
    
    public static void main(String[] args) throws IOException {
        Reader.init();
        int N=Reader.nextInt();
      	int V[]=new int[N];
      	read(V, N);
      	PriorityQueue<Double> PQ=new PriorityQueue();
      	for(int i:V){
        	PQ.add((double)i);
        }
      	while(PQ.size()>1){
        	double a=PQ.poll();
          	double b=PQ.poll();
          	PQ.add((a+b)/2);
        }
      	print(PQ.poll());
      
    }

    static int mod=1000000007;
    
    public static void read(int arr[], int N) throws IOException{ for(int i=0;i<N;i++){ arr[i]=Reader.nextInt(); } }
    public static void read(String arr[], int N) throws IOException{ for(int i=0;i<N;i++){ arr[i]=Reader.next(); } }
    
    public static void print(Object O){ System.out.println(O); }
    
    public static void display(int arr[]){ System.out.println(Arrays.toString(arr)); }
    public static void display(int arr[][], int N){ for(int i=0;i<N;i++){ System.out.println(Arrays.toString(arr[i])); } }
  
}

class Reader {
    static BufferedReader reader;
    static StringTokenizer tokenizer;

    static void init() {
        reader=new BufferedReader(new InputStreamReader(System.in));
        tokenizer=new StringTokenizer("");
    }

    static String next() throws IOException {
        while (!tokenizer.hasMoreTokens() ) {
            tokenizer=new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }

    static int nextInt() throws IOException { return Integer.parseInt(next()); }
    static double nextDouble() throws IOException { return Double.parseDouble(next()); }
    static long nextLong() throws IOException { return Long.parseLong(next()); }
    static String nextLine() throws IOException { return reader.readLine(); }
}
/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