Remaining archivelog files to restore

select
count(case when (checkpoint_change#>=0 or checkpoint_change# is null) then 3 END) as Total, 
count(case when checkpoint_change# <>0 then 2 END) as Restored, 
count(case when (checkpoint_change#=0 or checkpoint_change# is null) then 1 END) as Remained 
from v$datafile_header;