What is the output of

Declare @t table(id int identity, col1 int, col2 int, col3 int, col4 int, col5 int)
insert into @t values(23,33,44,55,66),(101,11,304,55,6),(7,3,5,9,1),(4,5,3,6,7),(1,2,3,4,5)

select max(col) from
(
select id, col from @t
unpivot (col for cols in (col1,col2,col3)) as unpivott
) as p
group by id