title: String not in regular expression
body: <p>I want to use Regex to find matches in a string. There are other ways to find the pattern I am looking for, but I am interested in the Regex solution. </p>
  
  <p>Concider these strings </p>
  
  <pre><code>"ABC123"
  "ABC245"
  "ABC435"
  "ABC Oh say can You see"
  </code></pre>
  
  <p>I want to match the find "ABC" followed by ANYTHING BUT "123". What is the correct regex expression? </p>