WITH tmp (l_name, id ,cnt) AS
	(SELECT  x.last_name, x.employee_id, COUNT(y.manager_id)
		FROM employee x, employee y
		WHERE (y.manager_id = x.employee_id AND (YEAR(CURRENT_TIMESTAMP )- YEAR(y.hire_date) < 30 ))
		GROUP BY x.employee_id, x.last_name)
SELECT *
	FROM tmp 
	WHERE (cnt = (SELECT MAX(cnt)
					FROM tmp))