use strict;

chomp(my @CIDR = <DATA>);
foreach (@CIDR)
{
  if (/\//) {
    # expand the address list
    my ($base, $range) = /(\d+\.\d+\.\d+\.)(.*)/;
    my ($r0, $r1) = split /\//, $range;
    if ($r1 < $r0) {
        die "invalid ip range" if length($r1) >= length($r0);
        $r1 = substr($r0, 0, length($r0) - length($r1)) . $r1;
    }
    print "$base$_\n" for $r0 .. $r1;
  } elsif (/-/) {
    my ($base, $from, $to) = /(\d+\.\d+\.\d+\.)(\d+)-\d+\.\d+\.\d+\.(\d+)/;
    print "$base$_\n" for $from .. $to;
  } else {
    # singular IP address
    print "$_\n";
  }
}

__DATA__
192.168.0.1
172.18.0.0/5
172.19.1.0/4
172.20.2.0/8
172.21.3.128/130
100.0.0.1-100.0.0.3
172.21.3.128/110

##</code><code>##

192.168.0.1
172.18.0.0
172.18.0.1
172.18.0.2
172.18.0.3
172.18.0.4
172.18.0.5
172.19.1.0
172.19.1.1
172.19.1.2
172.19.1.3
172.19.1.4
172.20.2.0
172.20.2.1
172.20.2.2
172.20.2.3
172.20.2.4
172.20.2.5
172.20.2.6
172.20.2.7
172.20.2.8
172.21.3.128
172.21.3.129
172.21.3.130
100.0.0.1
100.0.0.2
100.0.0.3
invalid ip range at p20.pl line 12, <DATA> line 7.