#P5253. [JSOI2013] 丢番图
[JSOI2013] 丢番图
Description
Consider the following Diophantine equation:
$$\frac{1}{x}~+~\frac{1}{y}~=~\frac{1}{n}~,(x,y,n~\in~\mathbb{N}^+)$$Xiao G is very interested in the following question: for a given positive integer , how many essentially different solutions satisfy the equation above? For example, when , there are three essentially different solutions :
Obviously, for larger , it is meaningless to list all essentially different solutions. Can you help Xiao G quickly find, for a given , the number of essentially different solutions to the equation above?
Input Format
One line with only one integer .
Output Format
Output one line with one integer, representing the answer.
4
3
Hint
Constraints
For all testdata, it is guaranteed that .
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