import java.util.Arrays;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = Integer.parseInt(sc.next());
		double[] V = new double[N];
		for(int i = 0;i < N;i++){
			V[i] = Double.parseDouble(sc.next());
		}
		sc.close();
		Arrays.sort(V);
		for(int i = 0;i < N-1;i++){
			V[i+1] = (V[i] + V[i+1]) / 2;
		}
		System.out.println(V[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