open(IN,"in.txt");
while(<IN>)
{
	if($_=~m/^\n/)
	{
        	$tell_val=tell();
	}
        if($_=~m/^\d+/)
        {
        $has{$&}=$tell_val if($tell_val ne '');
        }
}
open(OUT,">output.txt");
foreach(sort{$a<=>$b}(keys %has))
{
        seek(IN,$has{$_},0);
        $line=<IN>;
        print OUT $line;
        print $_;
}