The cows have been sent on a mission through space to acquire a new
milking machine for their barn. They are flying through a cluster
of stars containing N (1 <= N <= 50,000) planets, each with a trading
post.
The cows have determined which of K (1 <= K <= 1,000) types of
objects (numbered 1..K) each planet in the cluster desires, and
which products they have to trade. No planet has developed currency,
so they work under the barter system: all trades consist of each
party trading exactly one object (presumably of different types).
The cows start from Earth with a canister of high quality hay (item
1), and they desire a new milking machine (item K). Help them find
the best way to make a series of trades at the planets in the cluster
to get item K. If this task is impossible, output -1.
BZPRO