?????8??6? ?“??”??,????6??,8??6?16??????50????????????????????,??????????????,?4?????,?????????????????????????????????????,????????????2????,???1??????1????????????,????

??:“??”??????? ????????????????:??? “??????????”????

?? ??????????????? 4???

????:1???????????:sn???????

2???????

3??????400?????

4??????????

5???????????

?????8??6? ?“??”??,????6??,8??6?16??????50????????????????????,??????????????,?4?????,?????????????????????????????????????,????????????2????,???1??????1????????????,????

??:“??”??????? ????????????????:???