A person is guilty of burglary if he: (a) Enters any building or part of a building as a trespasser with intent to: Steal anything in the building or part of the building or, Inflict GBH on any person therein or, Do unlawful damage to the building or anything therein (b) Having entered any building or part of a building as a trespasser, steals or attempts to steal anything therein or, Inflicts or attempts to inflict GBH on any person therein