provide the daily minimum amount of .45% normal saline that patient 15257 has received.
select min(inputevents_cv.amount) from inputevents_cv where inputevents_cv.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 15257 ) ) and inputevents_cv.itemid in ( select d_items.itemid from d_items where d_items.label = '.45% normal saline' and d_items.linksto = 'inputevents_cv' ) group by strftime('%y-%m-%d',inputevents_cv.charttime)