#!/usr/bin/perl -w

sub q { 
	$; = 1;                        # $; stores how many tries you've had; start at 1
	for (0..3) { 
		$;[$_] = int(rand(9))      # @; stores the correct four numbers; set it up here
	}
} 

sub _ {
	print @_
}

&q;

for (;;) {
	$: = $~ = 0;        # set $: (right number in the right spot) and $~ (right number) to 0
	_ "$/$; ";          # prints a newline then the number of tries you've had
	$_ = <>;            # read a line into $_
	
	if (/^\d{4}$/) {    # if the line is exactly 4 digits...
		@q = split //;  # @q holds the 4 digits
		
		--$#q;          # set $#q = 3, ignoring the newline at $q[4]
		$@ = -1;        # set $@ to -1
		
		# This loops through the input digits and checks for correctness
		
		for (@q) {      				   # set $_ to each of the 4 input digits
			$a = $_;   					# set $a to the current digit (why not leave it $_?)
			($a == $;[++$@]) && ++$:       # increment $: if you have a right number in the right spot
				|| (grep /$a/, @;) && ++$~ # else increment $~ if you have a right number in the wrong spot
		}
		
		_ "$~W$:B ";  # print out the total of right/wrong ($~W) and right/right ($:B)
		++$;;         # increment number of tries
		
		$: == 4       # if we have four right numbers all in the right spots
			| $; > 10 # or we have already had 10 tries
			&& _ (@;) # print out the correct answer
			&& &q     # and start the game over
	}
}