import java.util.*;
import java.lang.*;

public class Main {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        double[] v = new double[n];
        for (int i = 0; i < n; i++) {
            v[i] = sc.nextInt();
        }
        Arrays.sort(v);
        ArrayList<Double> q = new ArrayList<>();
        
        for (int i = 0; i < n; i++) {
            q.add(v[i]);
        }
        //System.out.println("---");
        while(q.size() > 1) {
            double val = (q.remove(0) + q.remove(0)) / 2;
            //System.out.println(val);
            q.add(val);
            Collections.sort(q);
        }
        System.out.println(q.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