Get quantity of days between two dates in C #, Asp.net

Question

This is the code of my two Textbox:

 

Textbox 1:

<asp:TextBox ID="txtDate1" runat="server" ReadOnly = "true"></asp:TextBox>

Textbox 2:

<asp:TextBox ID="txtDate2" runat="server" ReadOnly = "true"></asp:TextBox>

This is the code of my JQUERY:

<script>
$(function () {
$("[id*=txtDate1]").datepicker({
  showOn: "button",
   buttonImage: "images/calendario.png",
       buttonImageOnly: true,
   buttonText: "a",
   minDate: 0,
  maxDate: 2,
      dateFormat: 'dd-mm-yy' }); });
 </script>

<script>
     $(function () {
    $("[id*=txtDate2]").datepicker({
    showOn: "button",
    buttonImage: "images/calendario.png",
    buttonImageOnly: true,
    buttonText: "a",
    minDate: 2,
    dateFormat: 'dd-mm-yy' }); });
 </script>

This is the code i was writing..on C# Asp.net

DateTime fechaUno = Convert.ToDateTime(txtDate1.Text);
DateTime fechaDos = Convert.ToDateTime(txtDate2.Text);
TimeSpan difFechas = fechaDos.Subtract(fechaUno);

I want to print the result in days in a variable