???????? ??? ???? ????????? ????????? ??????? ??? ???????????? ?????? {??? ???????????? ??? ?????? ????? ?????? ???????? ??? ??????? . ???????? ??????? ?? ??????? ?????? ?????? ???????? ????????????????? ??? ????? ????????? {??? ???????????? ???. ??????? ????????? ???????????? ?? ?? ???????????? ?? ???? ?? ???????????????