import java.io.*;
import java.util.*;

public class reagents_av {

	FastScanner in;
	PrintWriter out;
	final String fileName = "reagents".toLowerCase();

	void solve() {
		int n = in.nextInt();
		int[] a = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = in.nextInt();
		}
		Arrays.sort(a);
		double result = a[0];
		for (int i = 1; i < n; i++) {
			result = (result + a[i]) / 2;
		}
		out.println(result);
	}

	void run() {
		try {
			in = new FastScanner(fileName + ".in");
			out = new PrintWriter(fileName + ".out");
			solve();
			out.close();
		} catch (Exception e) {
			e.printStackTrace();
			System.exit(1);
		}
	}

	class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		public FastScanner(String s) {
			try {
				br = new BufferedReader(new FileReader(s));
			} catch (FileNotFoundException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}
	}

	public static void main(String[] args) {
		new reagents_av().run();
	}
}
