Create tag from filename

Hello,

I have a bunch of filenames that I would like to use to create the tracknumbers from.

For example:
2007_014[CD][PB] Gerard Joling - Maak Me Gek.mp3
The track number should be 14

Note that there are a few with an "a'" or "b", for example
2007_269a[CD][PB] Katie Melua - Shy Boy.mp3
The track should be 269 here.

I know how to remove the first part ('" 2007_'"), by entering:

2007_%track%

but how do I remove the last part ("[CD][PB].....")?

Expand that to
2007_%track%[%dummy%
To get rid of the letters in the track number, run an action of the type "Format value afterwards or use Convert>Tag-Tag for TRACK
Format string: $num(%track%,1)

@ohrenkino
It worked! Thanks a lot!