what is patient 24330's daily maximum potassium level in 04/2104?
select max(labevents.valuenum) from labevents where labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 24330 ) and labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'potassium' ) and strftime('%y-%m',labevents.charttime) = '2104-04' group by strftime('%y-%m-%d',labevents.charttime)