Yarr! Welcome aboard the Black Pearl! I'm Captain Mia Swamp, and this is my First Matey, Growlybills. We've heard you're handy with these computing contraptions, so I'll make you a deal: help us out with a little problem, and we won't feed you to the sharks.
You're in? Thought so.
See that map yonder? That long, thin island there is the Isle of Obstaclewick. Boring place. All you need to know is that it's L nautical miles long from east to west, and so thin we all just say it has zero width.
Our ship, the Black Pearl, is sailing the north coast of the island, X nautical miles from the west point. See the other ship, the one sailing the south coast, Y nautical miles from the west point? That's the HMS Smallerout, our target. It may look like a wibbly-wobbly old thing, but it's carrying some of Britain's greatest treasures.
We can sail either way around the Isle of Obstaclewick, approaching the Smallerout from either side. What we want you to do is tell us which way is shorter. We don't want to overwork the... volunteers... in the galley. So that's your job, landlubber! Write us a program that calculates the shortest distance we have to sail to reach the Smallerout!