???6??????17?????? ??????,??????,???16???????,??????????????????????????25?,??????????????????

????:?????(ABC)??????

???????????????,????????,????????????,????????????,??,???????????????40????(64??????)????,???????

??,??

?????????????,??,???,????????,?????????????,???

??????????:????? “???????”_????

?? ? ??????????????2???

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

2???????

3??????????

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

5???sn??

???6??????17?????? ??????,??????,???16???????,??????????????????????????25?,??????????????????

????:?????(ABC)??????

???????????????,????????,????????????,????????????,??,???????????????40????(64??????)????,???????

??,??

?????????????,??,???,????????,?????????????,???

??????????:?????