Strings & Patterns Learning Mode

How would you retrieve the first e-mail address if you run this code?

<?php
$subject = "purr for no reason or eat prawns daintily with a claw then
lick paws mycat@catsaregreat.com clean wash down prawns with a lap of
carnation milk then retire to the warmest spot on the couch to claw";
$pattern = "#(\S*)@(\w*).(\S*)#";
$matches = [];
preg_match($pattern, $subject, $matches);
// how do I echo the full email address?