my %class_c;
for my $ip (keys %IPs) {
    my $class_c = get_class_c_from_ip($ip);
    my $integer = convert_quad_ip_to_int($ip);
    my $bit = $integer - first_integer_in_class_c($class_c);
    vec($class_c{$class_c}, $bit, 1) = 1;
}
for $network (keys %class_c) {
    print "$network\n" if all_bits_are_1($class_c{$network});
}