#!/usr/bin/env perl
use warnings;
use strict;

my $prev = 0;
while (<DATA>) {
    if (/-----/) {
        print unless $prev;
        $prev = 1;
    }
    else {
        print;
        $prev = 0;
    }
}

__DATA__
aaaaaaaaaaaa
-----
-----
bbbbbbbbbbbb
-----
-----
-----
ccccccccccccc

##</code><code>##

aaaaaaaaaaaa
-----
bbbbbbbbbbbb
-----
ccccccccccccc