how much is the difference in weight for patient 2514 last measured on the first hospital visit compared to the value second to last measured on the first hospital visit?
select ( select chartevents.valuenum from chartevents where chartevents.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 2514 and admissions.dischtime is not null order by admissions.admittime asc limit 1 ) ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'admit wt' and d_items.linksto = 'chartevents' ) order by chartevents.charttime desc limit 1 ) - ( select chartevents.valuenum from chartevents where chartevents.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 2514 and admissions.dischtime is not null order by admissions.admittime asc limit 1 ) ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'admit wt' and d_items.linksto = 'chartevents' ) order by chartevents.charttime desc limit 1 offset 1 )