#!/usr/bin/perl
use strict;
use warnings;
while (my $line = <DATA>){
  chomp($line);
  $line = "0" . $line while length($line) < 9;
  my $first = substr($line, 0, 3);
  my $second= substr($line, 3, 2);
  my $third = substr($line, 5, 4);
  my $str = $first . '-' . $second . '-' . $third;
  print $str . "\n";
}

__DATA__
458430764
453453214
462634878
453990002
462755714
631036456
466917461
467172570
454691673
258611036
42

##</code><code>##

if(length($line) != 9){
  warn "Bad data read (at line $.): '$line' length is not correct.\n";
  next; # skip processing this line
}
if ($line !~ /^\d+$/){
  warn "Bad data read (at line $.): '$line' not numerical.\n";
  next; # skip processing this line
}