Create XElement with namespace in CSharp

using System;//from  w w w . j  a  va2  s .c om
using System.Linq;
using System.Xml.Linq;
using System.Collections;
using System.Collections.Generic;


public class MainClass{
   public static void Main(){
   
        XNamespace aw = "http://www.domain.com";
        XElement xmlTree1 = new XElement(aw + "Root",
            new XElement(aw + "Child1", 1),
            new XElement(aw + "Child5", 5),
            new XElement(aw + "Child6", 6)
        );
        
        XElement xmlTree2 = new XElement(aw + "Root",
            from el in xmlTree1.Elements()
            where((int)el >= 3 && (int)el <= 5)
            select el
        );
        Console.WriteLine(xmlTree2);
   }
}