instruction: how many days have it elapsed since the last time patient 31854 stayed in the careunit ccu during this hospital encounter?
response: SELECT 1 * (STRFTIME('%j', CURRENT_TIME()) - STRFTIME('%j', transfers.intime)) FROM transfers WHERE transfers.hadm_id IN (SELECT admissions.hadm_id FROM admissions WHERE admissions.subject_id = 31854 AND admissions.dischtime IS NULL) AND transfers.careunit = 'ccu' ORDER BY transfers.intime DESC LIMIT 1