what was the difference between the total amount of patient 702's input and output?
select ( 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 = 702 ) ) ) - ( select sum(outputevents.value) from outputevents where outputevents.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 702 ) ) )