From Bug in "Fireflies" makes it unwinnable

I guess this isn’t a spoiler. I saw it announced on the IFComp main page:

Actually, the game is winnable; you don’t need to buy anything from the store. (You’ll probably need to read the source to do so.)

In the source, he’s using “gp” in place where he meant to use “gd” – and “gp” isn’t defined (so it’s zero – you never have money). I fixed it, but I can’t re-compile.