how much clonazepam was last prescribed in the last hospital visit to patient 88404?
select prescriptions.dose_val_rx from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 88404 and admissions.dischtime is not null order by admissions.admittime desc limit 1 ) and prescriptions.drug = 'clonazepam' order by prescriptions.startdate desc limit 1