instruction: how many patients diagnosed with ac post hemorrhag anemia are administered via ng drug route?
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 = "Ac posthemorrhag anemia" AND prescriptions.route = "NG"