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() {
XDocument xDocument =
new XDocument(new XElement("Books",
new XElement("Book",
new XElement("FirstName", "J"),
new XElement("LastName", "R"))));
XProcessingInstruction xPI1 = new XProcessingInstruction("Book", "out-of-print"); xDocument.AddFirst(xPI1);
XProcessingInstruction xPI2 = new XProcessingInstruction("ParticipantDeleter",
"delete"); XElement outOfPrintParticipant = xDocument.Element("Books")
.Elements("Book")
.Where(e => ((string)((XElement)e).Element("FirstName")) == "J"
&& ((string)((XElement)e).Element("LastName")) == "R")
.Single();
outOfPrintParticipant.AddFirst(xPI2);
Console.WriteLine(xDocument);
}
}