#!/usr/bin/perl -w

use strict;
#use IO::All;
use Data::Dumper;

my %result;

for my $l (<DATA>) {

	my ($cod,$desc) = ($l =~/(\d*) (.*)/);
	my ($c1,$c2,$c3,$c4,$c5) = unpack ("A1 A1 A1 A1 A1",$cod);
	$result{$c1}{$c2}{$c3}{$c4}{$c5} .= $desc;
}
print Dumper \%result;


__DATA__
1 ITEM
11 Sub Item 1
111 Item X
112 Item
1121 Another Item
11212 And Another Item
12 Sub Item 2

##</code><code>##

$VAR1 = {
  '1' => {
      '' => {
         '' => {
           '' => {
              '' => 'ITEM'
              }
          }
      },
      '1' => {
          '' => {
             '' => {
                '' => 'Sub Item 1'
                }
             },
             '1' => {
                 '' => {
                    '' => 'Item X'
                    }
              },
              '2' => {
                  '' => {
                     '' => 'Item'
                     },
                     '1' => {
                         '' => 'Another Item',
                         '2' => 'And Another Item'
                         }
                     }
               },
       '2' => {
           '' => {
              '' => {
                 '' => 'Sub Item 2'
                 }
              }
           }
       }
};

##</code><code>##

$VAR1 = {
   '1' => {
      '0' => 'ITEM',
	  '11' => {
	      '0' => 'Sub Item 1',
		  111 => 'Item X',
		  112 => {
		      '0' => 'Item',
			  '1121' => {
			         '0' => 'Another Item',
					 '11212' => 'And Another Item'
					 }
			  }
		  },
	  '12' => 'Sub Item 2'
	  }
    }		  
}