#!/usr/local/bin/perl
#
use strict;
use warnings;
use Set::IntSpan::Fast;

my @sequence_numbers = map {int($_)} (<DATA>);

my $set = Set::IntSpan::Fast->new();
$set->add_range(1,9999);
$set->invert();
$set->add(@sequence_numbers);
$set->invert();
print $set->as_string() . "\n";

__DATA__
9996 
9998 
9999 
0001 
0003 
0005