import java.util.*;


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

		int[] numArray = new int[n];

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

        Arrays.sort(numArray);
        double value = (numArray[0] + numArray[1]) / 2.0;
        for(int i = 2; i < n; i++){
            value = (value + numArray[i]) / 2.0;
        }

        System.out.println(value);

	}
}
/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