title: Count the values for a string if the rows are hidden
body: <p>I want to count where:</p>
  
  <ul>
  <li>column A contains "a"</li>
  <li>the rows containing "a" are hidden.</li>
  </ul>
  
  <p>For example:</p>
  
  <p>If rows 2 &amp; 5 (containing "a") are hidden the output should be 2 (excluding the visible "a" in row 3).</p>
  
  <p><img src="https://i.stack.imgur.com/p7A5P.gif" alt="enter image description here"></p>