Simple depth question

hi,

Suppose I have 5 MC’s with a button in/under each MC.

How can I, by pressing any one of the MC’s/buttons, make this one always appear BEHIND the four otherMC’s?

I know how to make it appear IN FRONT OF the others

MC.swapDepths(0);

but how to do it the other way around?
Can’t be too hard!

Thank you,
Jerryj.