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.

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 $\leq K$.

Constraints

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

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

见题面 Input 部分

见题面 Output 部分