calculate the total amount of the input from patient 19428 since 12/07/2105.
select sum(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 = 19428 ) ) and strftime('%y-%m-%d',inputevents_cv.charttime) >= '2105-12-07'