import java.io.PrintWriter;
import java.util.*;

public class Main {

    static String br = System.getProperty("line.separator");
    static Scanner sc  = new Scanner(System.in);

    public static void main(String[] args){
        int N = nextInt();

        double[] v = new double[N];
        for(int i=0; i<N; i++){
            v[i] = nextInt();
        }

        Arrays.sort(v);

        for(int i=0; i<N-1; i++){
            v[i+1] = (v[i]+v[i+1])/2.0;
        }

        println(v[N-1]);
    }

    //各桁の和
    public static int sumDigits(long n) {
        int sum = 0;
        while (n != 0) {
            sum += n % 10;
            n /= 10;
        }
        return sum;//合計を返す
    }

    //最大公約数gcd
    static long gcd (long a, long b) {
        long temp;
        while ((temp = a % b) != 0) {
            a = b;
            b = temp;
        }
        return b;
    }
    //最小公倍数lcm
    static long lcm (long a, long b) {
        long temp;
        long c = a;
        c *= b;
        while((temp = a%b)!=0) {
            a = b;
            b = temp;
        }
        return (c/b);
    }
    static int nextInt(){
        return Integer.parseInt(next());
    }
    static Long nextLong(){
        return Long.parseLong(next());
    }
    static String next(){
        return sc.next();
    }
    static void println(Object o){
        PrintWriter out = new PrintWriter(System.out);
        out.println(o);
        out.flush();
    }
   static void print(Object o){
       PrintWriter out = new PrintWriter(System.out);
       out.print(o);
       out.flush();
    }
}

/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