account -  fld-Total sal-intger r currncy

contact -fld  -sal of cntct-intger r currncy

when ever we create cntct  and sal is added in the field all cntct sal of total should be updated in account total sal field

Task-ex: if we have 5 cntcts of sal(10.000,25.0000,55.444,22.000,77.0000) while creating f recrd and updatng the recrd in sal fld in cntcts
it should be total in accnt fild total sal.?