in 03/2104, when was the last time that patient 14982 was prescribed both allopurinol and ezetimibe at the same time?
select t1.startdate from ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'allopurinol' and admissions.subject_id = 14982 and strftime('%y-%m',prescriptions.startdate) = '2104-03' ) as t1 join ( select admissions.subject_id, prescriptions.startdate from prescriptions join admissions on prescriptions.hadm_id = admissions.hadm_id where prescriptions.drug = 'ezetimibe' and admissions.subject_id = 14982 and strftime('%y-%m',prescriptions.startdate) = '2104-03' ) as t2 on t1.subject_id = t2.subject_id where datetime(t1.startdate) = datetime(t2.startdate) order by t1.startdate desc limit 1