instruction: provide the number of patients whose age is less than 41 and procedure long title is insertion of drug-eluting coronary artery stent(s)?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN procedures ON demographic.hadm_id = procedures.hadm_id WHERE demographic.age < "41" AND procedures.long_title = "Insertion of drug-eluting coronary artery stent(s)"