How many advisors are in charge of advising all the students in 1st year?
advisors refers to p_id_dummy; students in 1st year refers to student = 1 and yearsInProgram = 'Year_1'
SELECT COUNT(T1.p_id_dummy) FROM advisedBy AS T1 INNER JOIN person AS T2 ON T1.p_id = T2.p_id WHERE T2.yearsInProgram = 'Year_1' AND T2.student = 1