???? ???? ??????? ?? ?????? ?????? ???? ???? ??? ??????? ?? ???? ????? ??????? ??????? . ???? ??? ??????? ??????? ???? ????? ??? ?????????. ????? ??????? ??????? ?????????. ????? ?????? ?????? ?????? ?? ???????? ???????. ???? ??????? ??????? ????? ????? ?? ???????? . Selecting ???? ????? ??????? ??? ????? ???? ?????? is important consid