// describe the class
class Book
{
     // class members
     protected string Name;
     protected int Price;

     // class constructor without parameters
     public Book()
     {
     }

     // class constructor with parameters
     public Book(string name, int price)
     {
          Name = name;
          Price = price;
     }

     // class methods
     public void SetName(string name)
     {
          // assign the title of the book
          Name = name;
     }

     public void SetPrice(int price)
     {
          // assign the price of the book
          Price = price;
     }

     public void ShowInfo()
     {
          // show information about the book on the screen
          Console.WriteLine("Title of the book " + Name + ", price " + Price);
     }
}

Book book1 = new Book();

using System;

namespace ConsoleApplication1
{
     // describe the class
     class Book
     {
          // class fields
          protected string Name;
          protected int Price;

          // class constructors
          public Book()
          {
          }

          public Book(string name, int price)
          {
               Name = name;
               Price = price;
          }

          // class methods
          public void SetName(string name)
          {
               // assign the title of the book
               Name = name;
          }

          public void SetPrice(int price)
          {
               // assign the price of the book
               Price = price;
          }

          public void ShowInfo()
          {
               // show information about the book on the screen
               Console.WriteLine("Title of the book " + Name + ", price " + Price);
          }
     }

     // main class of the program
     class Program
     {
          static void Main(string[] args)
          {
               // create a class object Book
               Book book1 = new Book(); // the class constructor is called Book()
               book1.SetName("Harry Potter"); // call the method SetName
               book1.SetPrice(20); // call the method SetPrice
               book1.ShowInfo(); // call the method ShowInfo
               // on the screen we will see "Title of the book Harry Potter, price 20"

               // create a class object Book
               Book book2 = new Book("The Three Musketeers", 30); // the class constructor is called Book(string, int)
               book2.ShowInfo(); // call the method ShowInfo
               // on the screen we will see "Title of the book The Three Musketeers, price 30"
          }
     }
}