Conditional formatting to highlight non-matches

I'm trying to help someone who has a legacy spreadsheet.

Column A contains location information that must adhere to a pre-defined set of location names with NO exceptions (there can't even be an extra space at the end of the location name). The problem is it's almost impossible to identify which cells deviate from the approved list.

I would like to set up conditional formatting that checks each cell in column A against the pre-defined set of approved names that is in another column, and highlights any column A cells that do NOT match.

I can get the MATCH function to show values that DO match, but not the ones that DON'T match.

Can anyone help?

Thanks!