#!/usr/bin/perl

use strict;
use warnings;

sub elide {
  my ($start,$end) = @_;

  my $len = length( $end );
  for ( reverse 0..$len ) {
    my $start_start = substr( $start, 0, $_ );
    last if $end =~ s/^$start_start//;
  }

  return ( $end ) ? $start . '-' . $end : $start;
}

while ( <DATA> ) {
  print elide( split ' ', $_ ), "\n";
}

__DATA__
1   32
4   19
28  39
34  123
321 321
324 329
325 349
340 509


##</code><code>##

1-32
4-19
28-39
34-123
321
324-9
325-49
340-509