Competitions

# Math problems 6-8 grade

# A * B + C

Positive integer **n** is given. How many tuples (**A**, **B**, **C**) of positive integers satisfy **A** * **B** + **C** = **n**?

#### Input

One positive integer **n** (**2** ≤ **n** ≤ `10`

).^{8}

#### Output

Print the required number of tuples.

Input example #1

3

Output example #1

3

Input example #2

11

Output example #2

27