How to ignore numbers being selected from a List<string>?
<p>I have a list of items such as</p>

<p>A1<br>
A2<br>
A3<br>
B1<br>
C1<br>
F1<br>
1A<br>
2A  </p>

<p>and I use the following code to get a list of distinct strings representing the first letter of each group:</p>

<pre><code>var result = groups.Select(xx =&gt; xx.Name.Substring(0, 1)).Distinct().ToList();
</code></pre>

<p>so this returns a list like follows:</p>

<p>A<br>
B<br>
C<br>
F<br>
1<br>
2  </p>

<p>This is all good, except for the numbers... Is there an easy way for me to modify the code to return only letters, so if it's a number it won't be added to the <code>results</code> group?</p>
