题目

英语翻译
Problem Description
Little Petya likes numbers a lot.He found that number 123 in
base 16 consists of two digits:the first is 7 and the second is 11.So the sum
of digits of 123 in base 16 is equal to 18.
Now he wonders what is an average
value of sum of digits of the number A written in all bases from 2 to
A-1.
Note that all computations should be done in base 10.You should find
the result as an irreducible fraction,written in base 10.
Input
Input contains one integer number A (3

提问时间：2021-01-09

答案

任意给一个10进制数A(3