#!/usr/bin/perl

# http://perlmonks.org/?node_id=1198153

use strict;
use warnings;
use Data::Dumper;

my $start;
my @answer;

for ( sort {$a <=> $b} map tr/\n//dr, <DATA> )
  {
  if( not defined $start or $_ > $start + 1000 )
    {
    push @answer, [ $_ ];
    $start = $_;
    }
  else
    {
    push @{ $answer[-1] }, $_;
    }
  }

print Dumper \@answer;

__DATA__
141326478
103194415
86004442
86004438
86004437
86004434
86004431
85280835
85280834
85280832
53250112
50137387
50137382
50137380
29223108
25694155
17916134