Umm not sure what to explain...

-n is used for an input loop for interaction

-l is used to get implicit EOL's

$, is set to space to make the bottles easier to count

I like map, and with $, a single print works fine.

The messages are ROT13, to make source viewing a pain, and eat char's...

Most of the body is syntax checking to prevent the user from entering char's
other than 1,2,3.
	1, 2, and 3 shifted right twice should be 0... if true they tried
	to take to many bottles...

	bitwise shifting twice with a floor catches negative values

	++, -- 	makes non-numerics into 0.

	||=4 makes 0 (including 0 from above)
	and null into an invalid entry caught above...

Logic
	The computer takes an even number(2) if an odd number of bottles remain

	Otherwise it takes 1 or 3.
	It chooses that which will let it win this turn, else it picks @ random

	Half the time the computergets to start first.
	The only cheap way to do this with -n was to have it complain
	and then order the user to go...