import java.util.*;
public 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] = (double)sc.nextInt();
      }
      Arrays.sort(v);
      for(int i = 1;i < n;i++){
      	v[i] = (v[i]+v[i-1])/2;
      }
      System.out.println(v[n-1]);
    }
}
