import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        List<Double> v = new ArrayList<>();
        for(int i = 0; i < n; i++){
            v.add(scan.nextDouble());
        }
        Collections.sort(v);
        double sum = 0;
        double a = 0;
        while(v.size() > 1){
            a = (v.get(0) + v.get(1)) / 2;
            v.remove(0);
            v.remove(0);
            v.add(a);
            Collections.sort(v);
        }
        System.out.println(v.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