title: Regular expression for extracting the prefix of a string
body: <p>I need a c# regular expression for extracting the prefix of a string which has a postfix of 2 characters and a number.</p>
  <p><strong>I MUST USE REGEX</strong></p>
  <p>example:</p>
  <blockquote>
  <p>input: &quot;ABCDZZ4321&quot;</p>
  <p>output: &quot;ABCD&quot;</p>
  </blockquote>
  <p>I want to cut the two 'Z' characters and the number at the end.</p>
  <p>Another example:</p>
  <blockquote>
  <p>input: &quot;ABCD4R4321&quot;</p>
  <p>output: &quot;ABCD&quot;</p>
  </blockquote>