what was the minimum platelet count value for patient 65786.
select min(labevents.valuenum) from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 65786 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'platelet count' )