using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using System.Xml;
using System.Xml.Linq;
public class MainClass {
public static void Main() {
XElement firstParticipant;
XDocument xDocument = new XDocument(new XDeclaration("1.0", "UTF-8", "yes"),
new XDocumentType("Books", null, "Books.dtd", null),
new XProcessingInstruction("Book", "out-of-print"),
new XElement("Books", firstParticipant =
new XElement("Book",
new XAttribute("type", "Author"),
new XElement("FirstName", "J"),
new XElement("LastName", "R")),
new XElement("Book",
new XAttribute("type", "Author"),
new XElement("FirstName", "E"),
new XElement("LastName", "B"))));
Console.WriteLine(firstParticipant.NextNode.PreviousNode);
}
}