#!/usr/bin/perl

# http://perlmonks.org/?node_id=1176395

use strict;
use warnings;

my @array;
$array[0]="0\n1\n2\n3\n";
$array[1]="4\n5\n6\n";
$array[2]="7\n8\n";
$array[3]="9\n";

my @result;

for my $start (0..$#array)
  {
  my $to = $start;
  $result[$to++] .= "\t" x !!$start . $1 while $array[$start] =~ /(.+)\n/g;
  }

print "$_\n" for @result;

##</code><code>##

0
1       4
2       5       7
3       6       8       9