###HUMAN: how many patients whose diagnoses long title is cellulitis and abscess of leg, except foot and drug route is po?, ###ASSISTANT: 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 = "Cellulitis and abscess of leg, except foot" AND prescriptions.route = "PO"