????:1???????????:???????

2???????

3??????????

4???????

5????sn??

2?????????????????12?,??????,?????54??,???? ???????? ? 2????????12?,??????,???????54?,???????? ? ? 2?????12??????,??,??54?,??? ? ?????? 2?????????????????12?????????????????,?,??54?????????????????,????? ? ???????? 2?????12???????,??????,?????????????????54?????,?????????????????? ????????????????? ?????? 2?12?,?????,?54?,????????(?)??????? ???????? ? 2???????12???????,?????????????????,?????54?,?????????????????? ?????? ????????????????? 2??12????????,????????,?????54?????,???????? ???????? ? ????????:??