#!/usr/bin/perl

use strict;
use warnings;

my @nums = split / /, shift;

my ($have_begin, $have_inc, $not_follow_inc, $str);

for (my $i = 0; $i < @nums; $i++) {
    no warnings 'uninitialized';
    if (!$have_begin && !$not_follow_inc) {
        $str .= $nums[$i];
        $have_inc = $nums[$i];
        $have_begin = 1;
    } elsif (($nums[$i+1] - $nums[$i]) == 1) {
        $have_inc++;
    } elsif ($not_follow_inc) {
        $str .= ', ' . $nums[$i];
        $str .= ', ' if $i != $#nums;
        $not_follow_inc = 0;
    } else {
        $str .= '-'.++$have_inc;
        $have_begin = 0;
        $not_follow_inc = 1;
    }
}

print "$str\n";

__INPUT__

1 2 3 5 7 8 9

__OUTPUT__

1-3, 5, 7-9