C# XML parsing. Need to get text

I have such code:

using System;
using System.IO;
using System.Xml.Serialization;

namespace ConsoleApp1
{
    [XmlRoot(ElementName = "doc")]
    public class Doc
    {
        [XmlElement(ElementName = "headline")]
        public string Headline { get; set; }
    }

    static class Program
    {
        static void Main(string[] args)
        {
            Doc res;

            var serializer = new XmlSerializer(typeof(Doc));
            using (var reader = new StringReader(File.ReadAllText("test.xml")))
            {
                res = (Doc) serializer.Deserialize(reader);
            }

            Console.Out.WriteLine(res.Headline.ToString());
        }
    }
}

My test.xml file contains such info:

<doc>
    <headline>AZERTY on the English <hlword>QWERTY</hlword> layout.
    </headline>
</doc>

When I try to parse it, I have an exception:

System.InvalidOperationException occurred
  HResult=0x80131509
  Message=There is an error in XML document (2, 35).
  Source=System.Xml
  StackTrace:
   at System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events)
   at System.Xml.Serialization.XmlSerializer.Deserialize(TextReader textReader)
   at ConsoleApp1.Program.Main(String[] args) in D:\Documents\Visual Studio 2017\Projects\ConsoleApp1\ConsoleApp1\Program.cs:line 24

Inner Exception 1:
XmlException: Unexpected node type Element. ReadElementString method can only be called on elements with simple or empty content. Line 2, position 35.

I need to get output as AZERTY on the English <hlword>QWERTY</hlword> layout. or AZERTY on the English QWERTY layout. from such files. What type need I to set to Headline property of Doc to get such text (maybe with calling ToString() property)?

P.S. I'm using Windows 10 with Creators Update with VisualStudio 2017 (15.3.3)

The error is telling you that it cannot parse <headline>AZERTY on the English <hlword>QWERTY</hlword> layout. to a simple string as it has a element in it. This is called a mixed type. To parse this you need to edit your XMLObject to something like this

[XmlRoot(ElementName = "doc")]
public class Doc
{
    [XmlElement(ElementName = "headline")]
    public Headline Headline { get; set; }
}

public class Headline
{
    [XmlText]
    public string Content { get; set; }

    [XmlElement(ElementName = "hlword")]
    public string HlWord { get; set; }
}