import java.util.*;

class Main {

	static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
		int N = sc.nextInt();
		int v[] = new int[N];
		for(int i=0;i<N;i++) {
			v[i]=sc.nextInt();
		}
		Arrays.sort(v);
      double ans = v[0];
		for(int i=1;i<N;i++) {
			ans = (ans+v[i])/2;
		}
		System.out.println(ans);
	}
}