import java.util.*;
 
class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int[] v = new int[N];
		Arrays.setAll(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);
	}
}