using System;

using System.Xml;

using System.Xml.Linq;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var xml = @"<colours xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'>

  <Red>

    <Shade id='1'>

      <colour>crimson</colour>

    </Shade>

    <Shade id='2'>

      <colour>raspberry</colour>

    </Shade>

    <Shade id='3'>

      <colour>lava</colour>

    </Shade>

    <Shade id='4'>

      <colour>scarlet</colour>

    </Shade>

    <Shade>

      <colour>test</colour>

    </Shade>

  </Red>

  <Green>

    <Shade id='1'>

      <colour>asparagus</colour>

    </Shade>

    <Shade id='2'>

      <colour>emerald</colour>

    </Shade>

    <Shade id='3'>

      <colour>lime</colour>

    </Shade>

    <Shade id='4'>

      <colour>avocado</colour>

    </Shade>

  </Green>

  <Blue>

    <Shade id='1'>

      <colour>cyan</colour>

    </Shade>

    <Shade id='2'>

      <colour>sapphire</colour>

    </Shade>

    <Shade id='3'>

      <colour>powder</colour>

    </Shade>

    <Shade id='4'>

      <colour>iris</colour>

    </Shade>

  </Blue>

</colours>";

        var MyData = XElement.Parse(xml);

        int count = MyData.Elements("Red")

                  .Elements("Shade")

                  .Where(o => (int?)o.Attribute("id") == 3)

                  .Count();

        Console.WriteLine(count);

    }

}