?? ???????????????????
????:1????????????:??sn??
2???????
3??????
4??????
5?????
???,?,?????????(??????????????)?
??????6???????11????????????(?)?????????,??,????????,??????????6?9????????????????10??20?;6?11???????????????7???30??????,????,???????????
????????????????????????????????????????????????????????????????????,??,???????????????????,???????????????;???????????????,?????,???????;?????,???????????,??????????;???????????????????,?24?????,??????,???????????????????????
???????????,??,???????????11????????????????9?30????????,????????????????
?«????????????»??????,?????????????????(?????????????????????)
??:??????????????