instruction: count the number of patients whose diagnoses short title is ca in situ oral cav/phar and drug route is im?
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.short_title = "Ca in situ oral cav/phar" AND prescriptions.route = "IM"