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Score : $300$ points

### 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