Challenge 2: Calling a Method Directly on an int Literal — Possible Solution
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Program.cs:

Console.WriteLine(42.ToString());

// This compiles and runs without error in C# because int is not a
// separate, non-object primitive category the way it is in Java --
// int is literally a built-in alias for System.Int32, a real struct.
// A struct is a genuine type in the .NET type system with its own
// methods, so calling ToString() directly on 42 is calling a real
// method on a real (if lightweight) struct instance, no different in
// principle from calling a method on any other object.
//
// In Java (java1-2), int is NOT an object at all -- it belongs to a
// completely separate, non-object category of primitive types.
// Attempting `42.toString()` directly on a raw int literal would not
// compile in Java; the int would first need to be autoboxed into an
// Integer (its wrapper class) before any method could be called on
// it -- e.g. Integer.valueOf(42).toString(), or relying on
// autoboxing to do that conversion implicitly in a context that
// requires an object.

Output:

    42

WHY THIS WORKS AS AN ANSWER
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This demonstrates the chapter's own "built-in types are just structs"
reveal directly, and the explanation correctly identifies WHY this
differs from Java: C#'s int is a genuine struct/object, while Java's
int is a wholly separate, non-object primitive category requiring
boxing before any method call is possible.