(1) A person commits the offense of criminal trespass in the second degree if: (a) The person knowingly enters or remains unlawfully in or upon premises that are enclosed in a manner designed to exclude intruders or are fenced; (b) The person enters or remains unlawfully in or upon commercial premises after a reasonable warning or request to leave by the owner or lessee of the commercial premises, the owner's or lessee's authorized agent, or a police officer; provided that this paragraph shall not