Problem Statement

You are given a positive integer $N$.
Find the number of quadruples of positive integers $(A,B,C,D)$ such that $AB + CD = N$.

Under the constraints of this problem, it can be proved that the answer is at most $9 \\times 10^{18}$.

Constraints

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

Input

The input is given from Standard Input in the following format:

$N$

Output

Print the answer.

Sample Input 1

4

Sample Output 1

8

Here are the eight desired quadruples.

• $(A,B,C,D)=(1,1,1,3)$
• $(A,B,C,D)=(1,1,3,1)$
• $(A,B,C,D)=(1,2,1,2)$
• $(A,B,C,D)=(1,2,2,1)$
• $(A,B,C,D)=(1,3,1,1)$
• $(A,B,C,D)=(2,1,1,2)$
• $(A,B,C,D)=(2,1,2,1)$
• $(A,B,C,D)=(3,1,1,1)$

Sample Input 2

292

Sample Output 2

10886

Sample Input 3

19876

Sample Output 3

2219958