import java.util.*;

class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        double[] stf = new double[n];

        for(int i = 0;i < n;i++){
            stf[i] = sc.nextDouble();
        }

        Arrays.sort(stf);

        for(int i = 0;i < n-1;i++){
            stf[i+1] = (stf[i]+stf[i+1])/2.0;
        }
        
        System.out.println(stf[n-1]);

    }
}
/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