instruction: count the number of patients whose diagnosis icd9 code is 43401 and drug route is sl.
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN prescriptions ON demographic.hadm_id = prescriptions.hadm_id WHERE diagnoses.icd9_code = "43401" AND prescriptions.route = "SL"