Contest Duration: - (local time) (120 minutes) Back to Home
A - A*B*C /

Time Limit: 2 sec / Memory Limit: 1024 MB

### 制約

• 1\leq K\leq 2\times 10^5
• K は整数である

### 入力

K


### 入力例 1

2


### 出力例 1

4


(1,1,1),(1,1,2),(1,2,1),(2,1,1) が条件を満たします。

### 入力例 2

10


### 出力例 2

53


### 入力例 3

31415


### 出力例 3

1937281


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