instruction: count the number of prescribed drugs patient 015-33415 has been prescribed in the last hospital encounter.
response: SELECT COUNT(*) FROM medication WHERE medication.patientunitstayid IN (SELECT patient.patientunitstayid FROM patient WHERE patient.patienthealthsystemstayid IN (SELECT patient.patienthealthsystemstayid FROM patient WHERE patient.uniquepid = '015-33415' AND NOT patient.hospitaldischargetime IS NULL ORDER BY patient.hospitaladmittime DESC LIMIT 1))