Indexing system

It's a simple enough problem

[adni18]

Hi. I have a script (shown below) to take entries from an array, sort them alphabetically, and make folders for every 3 files in the index. Then the script should make 3 files in each directory ("fileXXX.ind"). However, I do not know how to do this. Please help!

#!/usr/bin/perl

use CGI;

use pageenc;

use POSIX qw(ceil floor);

my $track1;
my $track2=1;

# pages to index #
my @pages=(4,2,3,1,5,6,9,7,8);

@pages=sort(@pages);

my $enc1=new bots::pageenc;

my $track1=@pages;
$track1=ceil($track1/3);

while($track2 <= $track1)
{
mkdir("index".sprintf("%.3"."d", $track2));
$track2++;
}

<STDIN>;

[adni18]

nevermind. I figured it out; I should do the following to determine which directory to put it in:

floor($number/3)+1