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 XElement("Books", firstParticipant =
new XElement("Book",
new XAttribute("type", "Author"),
new XElement("FirstName", "J"),
new XElement("LastName", "R"))));
Console.WriteLine(xDocument);
firstParticipant.SetElementValue("FirstName", "Joseph");
firstParticipant.SetElementValue("MiddleInitial", "C");
firstParticipant.SetElementValue("LastName", null);
Console.WriteLine(xDocument);
}
}