How many classes are professor whose last name is Graztevski has?
CREATE TABLE employee (
    EMP_NUM VARCHAR,
    EMP_LNAME VARCHAR
)

CREATE TABLE CLASS (
    PROF_NUM VARCHAR
)
SELECT COUNT(*) FROM employee AS T1 JOIN CLASS AS T2 ON T1.EMP_NUM = T2.PROF_NUM WHERE T1.EMP_LNAME = 'Graztevski'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: How many classes are professor whose last name is Graztevski has? ### Input: CREATE TABLE employee (
    EMP_NUM VARCHAR,
    EMP_LNAME VARCHAR
)

CREATE TABLE CLASS (
    PROF_NUM VARCHAR
) ### Response: SELECT COUNT(*) FROM employee AS T1 JOIN CLASS AS T2 ON T1.EMP_NUM = T2.PROF_NUM WHERE T1.EMP_LNAME = 'Graztevski'