Hello guys, I need a little advice on this one...

The CD's produced by a factory are damaged with probability 0.1 each (and independent on one another). The factory sell the CD's in packages of 3, and give the money back to the customer if a package contain more than 1 damaged CD. A customer bought 2 packages: package 1 and package 2.

T - The number of damaged CD's in package 1

S - The number of packages the customer got his money back for

Build the joint probability function of T and S.

I know that T={0,1,2,3) and S={0,1,2}

I also know that P(S=0,T=2)=P(S=0,T=3)=0

What next ?