title: Conditionally formatting cells if their value equals any value of another column
body: <p>I have data in the <code>A</code> and <code>B</code> columns. <code>B</code> column's data is mostly duplicates of <code>A</code>'s data, but not always. For example:</p>
  
  <pre><code>A
  Budapest
  Prague
  Paris
  Bukarest
  Moscow
  Rome
  New York
  
  B
  Budapest
  Prague
  Los Angeles
  Bukarest
  </code></pre>
  
  <p>I need to search the <code>A</code> column for the values in <code>B</code>. If a row matches, I need to change the row's background colour in <code>A</code> to red or something.</p>