Euclid's Pizza

You've just learned to hack using EXAs, and who wouldn't love a free pizza?

"Append your order (file 300) to the end of the order list (file 200). Note that all orders, including yours, will consist of exactly five keywords."
 * The achievement PIZZA_PARTY is also earned here.
 * Remember that you can SEEK since you do not care about the existing contents of the order list.