import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int N = sc.nextInt();
		
		double[] V = new double[N];
  		
		double ave = 0;
		int max = 0;
	    int max2 = 0;
		for(int i = 0 ;i<N;i++){
			V[i] = sc.nextInt();
        }
      
      	Arrays.sort(V);
      
      	for(int i = 1 ;i<N;i++){
			if(ave == 0){
              ave = (V[0] + V[1]) / 2;
            }else{
              ave = (ave + V[i]) /2;
            }
        }
 	  
      
		System.out.println(ave);
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz