need a tip

well i have filled the itab with data.

then i want to subtract the amount in 5th line for example with the amount in 4th.

i will be more clear.

i have pernr zkind ( =01 or =02) and the amount.

for each pernr.

if zkind is =02 the amount must be substracted with the amount that zkind = 01.

pernr zkind amount

1045 01 100

1046 01 100

1046 02 50

the resault that i want to take is this:

pernr zkind amount

1045 01 100

1046 01 50

1046 02 50