Unapplied amount query for Receipt Oracle Receivables

select
sum(decode(app.status ,'unapp' , 
     decode(upper(:p_in_curr_code ) , null , round(app.acctd_amount_applied_from, 2 ) ,                  app.amount_applied )
            , 'unid', decode(upper('eur'), null, round(app.acctd_amount_applied_from , 2 ) , app . amount_applied ) , 0 ) ) unapplied_amt
 from ar_receipt_methods rm ,
  ar_receivable_applications_all app ,
  ar_cash_receipt_history_all crh ,
  ar_cash_receipts_all rcpt
  where app.status                  in ( 'acc' , 'unapp' , 'unid')
and app.org_id                     = 83
and nvl(app.confirmed_flag, 'y')   = 'y'
and rcpt.cash_receipt_id           = app.cash_receipt_id
and nvl(rcpt.confirmed_flag ,'y' ) = 'y'
and crh.cash_receipt_id            = rcpt.cash_receipt_id
and crh.first_posted_record_flag   = 'y'
and rcpt.receipt_method_id         = rm.receipt_method_id
and rcpt.receipt_number      = :p_receipt_number
and rcpt.deposit_date        = :p_deposit_date
;