???? ????? ??????? ?? ?????? ?????? ???? ???? ??? ??????? ?? ???? ??? ????????. ???? ??? ??????? ??????? ???? ?????? ??? ???????. ????? ??????? ??????? ?????????. ????? ?????? ?????? ?????? ??????. ???? ??????? ??????? ????? ???? ?? ???????. ?????? ???? ????? ??????? ??? ????? ???? ?????? need to consider ??? factors. ?????, determine g