?? ???????????????????????????????????
????:1???????:????sn
2??????
3???????
4???????
5???????????
???12??1????????????? ??????????:???????????????????????????,??
?????????????:??????????????????12??1????????????? ??????????:???????????????????????????,??
?????????????:???????????????????:1???????:????sn
2??????
3???????
4???????
5???????????
???12??1????????????? ??????????:???????????????????????????,??
?????????????:???????????????