201130: [AtCoder]ARC113 A - A*B*C

Problem Statement

Given a positive integer $K$, find the number of triples of positive integers $(A, B, C)$ such that $ABC \leq K$. Two triples that only differ in the order of numbers are also distinguished.

Constraints

• $1\leq K\leq 2\times 10^5$
• $K$ is an integer.

Input

Input is given from Standard Input in the following format:

$K$

Output

Print the number of triples of positive integers $(A, B, C)$ such that $ABC \leq K$.

Sample Input 1

2

Sample Output 1

4

We have the following triples: $(1,1,1),(1,1,2),(1,2,1),(2,1,1)$.

Sample Input 2

10

Sample Output 2

53

Sample Input 3

31415

Sample Output 3

1937281