title: Simplify 2 REGEX into 1
body: <p>I have to detect a string that contains at least 1 uppercase letter different from the first one and don't contain lowercase letter. 
  For example : </p>
  
  <ul>
  <li><code>ABCD !</code> => acceptable case</li>
  <li><code>Tommy Tom</code> => not acceptable case </li>
  <li><code>Let something</code> => not acceptable case</li>
  </ul>
  
  <p>Here what I did so far using 2 Regex : </p>
  
  <pre><code>!Regex.IsMatch(input, @"[a-z]") &amp;&amp;  Regex.IsMatch(input, @"[A-Z]");
  </code></pre>
  
  <p>I'm looking for a solution using a single REGEX.</p>