You could try an action of the type "Format value"
Format string:$replace(%discnumber%,01/01,,01/1,,1/01,,1/1,)
I see problems, though for files that are disc number 01 of 10 (11, 12 etc) as "01/1" matches that. The same problem arises for 1/1.
Thank you, this recommandation only replace 1/1 by 1, my problem is that I don't want a discncumber If there is only one disc then written 1/1 OR 01/01 OR 1 OR 1/01 OR 01/1, I need two actions ?