class Book
{
     // class field
     protected string Name;

     // class method
     public void SetName(string Name)
     {
          this.Name = Name;
     }
}

class Program
{
     static void Main(string[] args)
     {
          // create a class object Book
          Book book1 = new Book();

          book1.SetName("Harry Potter");
          // book1.Name = "Harry Potter"
     }
}

class Book
{
     protected string Name;
     protected int Price;

     public Book(string name) : this(20)
     {
          Name = name;
     }

     public Book(int price)
     {
          Price = price;
     }
}
    
class Program
{
     static void Main(string[] args)
     {
          Book book1 = new Book("Wizard of the Sea");
          // book1.Name = "Wizard of the Sea"
          // book1.Price = 20
     }
}