sub parse {
  my $item = shift;
  return [ $item, $item =~ /^(\d+)([a-zA-Z]*)/ ];
}

sub sort_alphanum {
  $a->[ 1 ] <=> $b->[ 1 ] or
  $a->[ 2 ] cmp $b->[ 2 ];
}

my @sorted =
  map $_->[ 0 ],
  sort sort_alphanum
  map parse( $_ ), @old;