instruction: give me the number of patients whose diagnoses long title is regional enteritis of unspecified site and drug route is ou?
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.long_title = "Regional enteritis of unspecified site" AND prescriptions.route = "OU"