until 05/26/2100, what was the first value of arterial bp mean for patient 20165?
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 = 20165 ) ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'arterial bp mean' and d_items.linksto = 'chartevents' ) and strftime('%y-%m-%d',chartevents.charttime) <= '2100-05-26' order by chartevents.charttime asc limit 1