Regexp (delete alphanumerical caractere but not all of them)

Hi !

I'm not sure my title of really clear,

I'm treating a sequence of PNG image with maxmsp and my name files often look like that :

bliblablo0001.png,
bliblablo0002.png,
bliblablo000x.png...

but if I have a another version of bliblablo I will call it bliblablo2 and then I will have :

bliblablo20001.png,
bliblablo20002.png,
bliblablo2000x.png...

SO, I would like to isolate that name 'bliblablo' or 'bliblablo2' knowing than my files alwayz end by the four digits of the frame number.

I'm trying to doin it with Regexp because I know it is able to do it, I've already that little patch, I know I'm near but for the moment it delete all the digit :

I tried to search a bit on the forum before because i'm sure a prob like this as been already solved but with regexp that's hard to search, sorry then and thank for your help !