409707: GYM103688 I Equal Sum Arrays

Define function $$$f(n)$$$ to be the number of different arrays $$$a$$$ of positive integers, such that the sum of the elements in array $$$a$$$ equals to $$$n$$$.

For example, $$$f(3)=4$$$, and the four different arrays are $$$\{1,1,1\},\{1,2\},\{2,1\},\{3\}$$$.

You are given a positive integer $$$k$$$. Please find the answer of $$$f(k)$$$.

There is only one line in the input containing a single integer $$$k\ (1\leq k\leq 20)$$$.

Print a single integer: the answer of $$$f(k)$$$.

3

4

4

8