import java.io.*;
import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        
        final int N = Integer.parseInt(sc.next());
        int[] v = new int[N];
        for (int i = 0; i < N; i++) {
            v[i] = Integer.parseInt(sc.next());
        }
        
        Arrays.sort(v);
        double ans = (v[0] + v[1]) / 2.0;
        for (int i = 2; i < N; i++) {
            ans = (ans + v[i]) / 2.0;
        }
        
        out.println(ans);
        
        out.flush();
    }
}
/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