import java.util.Scanner;
import java.util.Arrays;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    double[] v = new double[N];
    int i = 0;
    int ptr = 1;
    int avgs = 0;

    for(i = 0; i < N; i++){
    	v[i] = sc.nextInt();
    }
    Arrays.sort(v);

    if(N == 2){
    	System.out.println((v[0] + v[1]) / 2);
    }else{
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	}
  }
} import java.util.Scanner; Scanner java.util import java.util.Arrays; Arrays 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];
    int i = 0;
    int ptr = 1;
    int avgs = 0;

    for(i = 0; i < N; i++){
    	v[i] = sc.nextInt();
    }
    Arrays.sort(v);

    if(N == 2){
    	System.out.println((v[0] + v[1]) / 2);
    }else{
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	}
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    double[] v = new double[N];
    int i = 0;
    int ptr = 1;
    int avgs = 0;

    for(i = 0; i < N; i++){
    	v[i] = sc.nextInt();
    }
    Arrays.sort(v);

    if(N == 2){
    	System.out.println((v[0] + v[1]) / 2);
    }else{
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	}
  } main {
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    double[] v = new double[N];
    int i = 0;
    int ptr = 1;
    int avgs = 0;

    for(i = 0; i < N; i++){
    	v[i] = sc.nextInt();
    }
    Arrays.sort(v);

    if(N == 2){
    	System.out.println((v[0] + v[1]) / 2);
    }else{
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	}
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc double[] v = new double[N]; v new double[N] N int i = 0; i 0 int ptr = 1; ptr 1 int avgs = 0; avgs 0 for(i = 0; i < N; i++){
    	v[i] = sc.nextInt();
    } i = 0; i = 0 i 0 i < N i N i++ i++ i {
    	v[i] = sc.nextInt();
    } {
    	v[i] = sc.nextInt();
    } v[i] = sc.nextInt() v[i] v i sc.nextInt() sc.nextInt sc Arrays.sort(v) Arrays.sort Arrays v if(N == 2){
    	System.out.println((v[0] + v[1]) / 2);
    }else{
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	} N == 2 N 2 {
    	System.out.println((v[0] + v[1]) / 2);
    } System.out.println((v[0] + v[1]) / 2) System.out.println System.out System System.out (v[0] + v[1]) / 2 (v[0] + v[1]) v[0] v 0 v[1] v 1 2 {
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	} for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    } i = 2; i = 2 i 2 i < N i N i++ i++ i {
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    } {
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    } v[0] = (v[0] + v[1]) / 2 v[0] v 0 (v[0] + v[1]) / 2 (v[0] + v[1]) v[0] v 0 v[1] v 1 2 v[1] = v[i] v[1] v 1 v[i] v i System.out.println((v[0] + v[1]) / 2) System.out.println System.out System System.out (v[0] + v[1]) / 2 (v[0] + v[1]) v[0] v 0 v[1] v 1 2 String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    double[] v = new double[N];
    int i = 0;
    int ptr = 1;
    int avgs = 0;

    for(i = 0; i < N; i++){
    	v[i] = sc.nextInt();
    }
    Arrays.sort(v);

    if(N == 2){
    	System.out.println((v[0] + v[1]) / 2);
    }else{
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	}
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    double[] v = new double[N];
    int i = 0;
    int ptr = 1;
    int avgs = 0;

    for(i = 0; i < N; i++){
    	v[i] = sc.nextInt();
    }
    Arrays.sort(v);

    if(N == 2){
    	System.out.println((v[0] + v[1]) / 2);
    }else{
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	}
  }
} Main
import java.util.Scanner;
import java.util.Arrays;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    double[] v = new double[N];
    int i = 0;
    int ptr = 1;
    int avgs = 0;

    for(i = 0; i < N; i++){
    	v[i] = sc.nextInt();
    }
    Arrays.sort(v);

    if(N == 2){
    	System.out.println((v[0] + v[1]) / 2);
    }else{
	    for(i = 2; i < N; i++){
	    	v[0] = (v[0] + v[1]) / 2;
	    	v[1] = v[i];
	    }
	    System.out.println((v[0] + v[1]) / 2);
	}
  }
}