use Socket;

my @blocks;

while(<DATA>) {
  chomp;
  my ($ip,$bits) = m,^(\d+(?:\.\d+){3})/(\d+)$, or next;
  push @blocks, unpack("B*",inet_aton($ip));
  substr($blocks[-1],-$bits) = "#" x $bits
    if $bits = 32 - $bits;
}

my $str = ";" . join(";", sort @blocks) . ";";
1 while $str =~ s/;([01]+)(#*);\1[01#]*;/;${1}${2};/g;
1 while $str =~ s/;([01]+)0(#*);\1.\2;/;${1}#${2};/g;

my @blocks = $str =~ /[10#]+/g;

foreach my $block (@blocks) {
  my $bits = 32 - ($block =~ tr/#/0/);
  print inet_ntoa(pack("B*", $block)),"/$bits\n";
}