Asp C# Regex for alphabet characters only

Here is a label which contains alphanumric and special characters.

Now to use Regex in asp .net we need to add Namespace

using System.Text.RegularExpressions;

Using asp c# code behind

        //==== Create Regex object and pass pattern.
        Regex reg = new Regex(@"[^a-zA-Z]");

        //===== Read Label value and replace all non alphabet characters with '-'
        string str = reg.Replace(lblValue.Text, "-");

        //==== Show output.
        Response.Write(str);

Output :