$pagina = 'Stack Overflow';
$url_post = str_replace(' ', '', $pagina);
$file = file_get_contents('http://graph.facebook.com/?ids='. $url_post);
$jsonObj = json_decode($file);

$fbcount = number_format($jsonObj->{$url_post}->{'likes'});
echo "A página $pagina tem $fbcount curtidas";