reverse midi control

[unguitar_2011]

hello,
I would like to have a midi cc to control two ( or more) different aux sends' knobs ( or ext. audio effect's gain knobs).
I need to be able to reverse its midi value so that when knob "A" is 100%, knob "B" is 0% and viceversa.
Is there an easy way for doing this ?

thanks,
Luca

[unguitar_2011]

solution found,
thanks to Yoseph
Luca