instruction: how many hours have it been since the last time patient 28447 began to stay in careunit csru on their current hospital encounter?
response: SELECT 24 * (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 = 28447 AND admissions.dischtime IS NULL) AND transfers.careunit = 'csru' ORDER BY transfers.intime DESC LIMIT 1