using System;

​

public class Program

{

    public static void Main()

    {

        /*string dene = "erewr";

        int a;

        for (a = 1; a <= 10; a++)

        {

            Console.WriteLine("Hello World");

            int age = Convert.ToInt32(Console.ReadLine());

        }

        */

        string[] cars = {"Volvo", "BMW", "Ford", "Mazda"};

        cars[0] = "Opel";

        Console.WriteLine(cars[0]);

        Console.WriteLine(Math.Sqrt(64)); 

    }

}