How many students are enrolled in some classes that are taught by an accounting professor?
select count(*) from class as t1 join enroll as t2 on t1.class_code = t2.class_code join course as t3 on t1.crs_code = t3.crs_code join department as t4 on t3.dept_code = t4.dept_code where t4.dept_name = 'Accounting'