(a) No person, after first being warned by a law enforcement officer, or where a sign or signs have been posted in accordance with this section, shall loiter, stand, sit or lie in or upon any public or quasi-public sidewalk, parking lot, street, driveway, curb, crossway, walkway area, mall, or that portion of private property utilized for public use, so as to hinder or obstruct unreasonably, the free passage of pedestrians or vehicles thereon; nor shall any person block or obstruct, or prevent the free access to the entrance to any building open to the public.
(b) Whoever violates this section is guilty of loitering, a misdemeanor of the third degree.