on their first hospital encounter what was the first id of the careunit of patient 19096?
select transfers.careunit from transfers where transfers.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 19096 and admissions.dischtime is not null order by admissions.admittime asc limit 1 ) and transfers.careunit is not null order by transfers.intime asc limit 1