instruction: give me the number of patients whose age is less than 50 and diagnoses long title is coronary atherosclerosis of native coronary artery?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id WHERE demographic.age < "50" AND diagnoses.long_title = "Coronary atherosclerosis of native coronary artery"