public class HelloWorld {
	public static void main(String[] args) {

		/*
		The first and last line of this program mark the start and end
		of a class named HelloWorld.
		The second and next-to-last line of this program mark the start
		and end of a method named main that belongs to class HelloWorld.
		*/

		System.out.println("Hello, world!");
		System.err.println("This is an error message.");
		System.exit(0);
	}
}