Automatic numbering of rows if there is some text in adjacent cell - with one exception

Hi,

as a beginer I need to ask for help - I can´t find anywhere on the web how to make this into formula or vba macro (which is automaticly updating numbering, if anything changes):

Automatic numbering of rows if there is some text in adjacent cell - with one exception - if there is text "XX" in adjacent cell, skip numbering of THIS ROW (leave cell blank) AND continue numbering.

I think the picture explains it better:

Bez názvu.jpg

Thank for any advice