(a)  Offense defined: A person commits the offense of burglary if, with the intent to commit a crime therein, the person:
 

• enters a building or occupied structure, or separately secured or occupied portion thereof that is adapted for overnight accommodations in which at the time of the offense any person is present;

• enters a building or occupied structure, or separately secured or occupied portion thereof that is adapted for overnight accommodations in which at the time of the offense no person is present;

• enters a building or occupied structure, or separately secured or occupied portion thereof that is not adapted for overnight accommodations in which at the time of the offense any person is present; or

• enters a building or occupied structure, or separately secured or occupied portion thereof that is not adapted for overnight accommodations in which at the time of the offense no person is present.

(b)  Defense: It is a defense to prosecution for burglary if any of the following exists at the time of the commission of the offense:
 

• The building or structure was abandoned.

• The premises are open to the public.

• The actor is licensed or privileged to enter.

(c)  Grading: Except as provided in paragraph (2), burglary is a felony of the first degree. As follows:

(i)   Except under subparagraph 

(ii), an offense under subsection (a)(4) is a felony of the second degree.
(ii)   If the actor's intent upon entering the building, structure or portion under subparagraph 

(i) is to commit theft of a controlled substance or designer drug as those terms are defined in section 2 of the act of April 14, 1972 (P.L.233, No.64), known as The Controlled Substance, Drug, Device and Cosmetic Act, burglary is a felony of the first degree.