How to get the sum for all the fields in classical reports

report .

tables:pa0008.

data: begin of itab occurs 0 ,
pernr like pa0008-pernr,
ansal like pa0008-ansal,
bet01 like pa0008-bet01 ,
end of itab .

data: v_sum type pa0008-bet01 .

select-options:s_pernr for pa0008-pernr .

start-of-selection .

select pernr
ansal
bet01
from pa0008
into table itab
where pernr in s_pernr .

loop at itab .
at end of pernr .
sum .
write:/ itab-pernr ,
itab-ansal,
itab-bet01.
endat .

endloop.