while (@a = split /\t|$/, <DATA>){
	$a[0] =~ /\d/ ? print "K $a[0] : " : next;
	print "positive number\n" and next if $a[1] == $a[2];
	print "negative number\n" and next if $a[1] == $a[3];
	print "author didn't specify that option\n";
}


__DATA__
K	I	B	S
1	2	2	3
2	4	3	4
3	5	5	2
4	9	1	3