Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE CLASS (PROF_NUM VARCHAR); CREATE TABLE employee (EMP_NUM VARCHAR, EMP_LNAME VARCHAR)
### Question:
How many classes are professor whose last name is Graztevski has?
### Answer:
SELECT COUNT(*) FROM employee AS T1 JOIN CLASS AS T2 ON T1.EMP_NUM = T2.PROF_NUM WHERE T1.EMP_LNAME = 'Graztevski'