Human Resource Machine/Year 30

Strategy
In this stage, you will once again pick a number off the conveyor belt and use indirect access to grab letters from the floor. This time however, after every time you grab a letter, you'll need to increment the number you placed in the box, and continue to grab letters from the floor until you encounter a zero. At that time, you'll grab a new number from the INBOX and start the process all over. There's only one available box for placing the number in, and that's box 24.

a:   INBOX COPYTO  24 b:   COPYFROM [24] JUMPZ   a    OUTBOX BUMPUP  24 JUMP    b

Optimizing
It is not possible to further optimize this solution.