how to mark numbers were sequential numbering is interrupted

Dear Experts:

I got thousands of figures in Column A of the current worksheet. They are sorted and have the following make-up:

90-001
90-002
90-003
90-005
90-007
90-009
90-020
90-021
90-022
90-025
.....
90-437

Is it possible by means of a formula or conditional formatting to show the ones where the sequence of '1' is not maintained,

Help is much appreciated. Thank you very much in advance.

I have attached a sample file for your convenience.

Regards, Andreas
sequential_numbering.xlsx