sub test {
   my $a = shift;
   die "Malformed value '$a'"
     if ($a !~ /(.)(.)(.)(..)(.+)/);

   my ($first,$second,$third,$fourth) = ($1,$2,$3,$4);

   return 0 if ($first !~ /(a)/);
   return 0 if ($second !~ /(d|p|t)/);
   return 0 if ($third !~ /(a|h|r|s|t)/);
   return 0 if ($fourth !~ /(aw|er|dd|cb|aa)/);
}

##</code><code>##

sub test {
   my $a = shift;
   $a =~ /(a)(d|p|t)(a|h|r|s|t)(aw|er|dd|cb|aa)(.+)/;
}