import java.util.*;

class Main{
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		double[] v = new double[n];
		for(int i = 0; i < n; i++){
			v[i] = sc.nextDouble();
		}
		Arrays.sort(v);
		double ans = (v[0]+v[1])/2;
		for(int i = 2; i < n; i++){
			ans = (ans+v[i])/2;
		}
		System.out.print(ans);
	}
}
