???????? ????????? ????????????? ?????? & ?????????? ????????? ????????? ??????? & ??????? ???????? ?????????????? ???? ?????????? ????? ??? ?? ??????? ??????????? ??????? ???????? ??????? ???????? & ??????? ??? ???? ?????? ???? ?? ????? ??? ?????????????? ??? ?? ????????? ??????????.“In theory, it‘s simple by definition, but in observe, it is