#! perl -sw
use strict;

while (<DATA>) {
	chomp;
	print sprintf('%-20s', $_),
		(/^[a-z][a-z-]+?[a-z]$/i and not /--/)
		? ' is '
		: ' is not ',
		'a valid word according to the rules specified.', $/;
}

__DATA__
brian0
brian-
-brian
bri--an
Bria-n
br-i-an
brian