my $split = join '/', split //, $id;
substr($split, -2, 2, '');
my $url = "$base_url/$split/$id/$id-h/$id-h.htm";

##</code><code>##

substr( ( my $split = join '/', split //, $id ), -2, 2, '');
my $url = "$base_url/$split/$id/$id-h/$id-h.htm";

##</code><code>##

( my $url = join '/', split //, $id ) =~
    s{(.*)/}{$base_url/$1/$id/$id-h/$id-h.htm}s;

##</code><code>##

my $url = join('/', 
    $base_url,
    $id =~ /(.)(?=.)/sg,
    $id,
    "$id-h",
    "$id-h.htm"
);