eolymp
Competitions

Полный перебор

A * B + C

Positive integer n is given. How many tuples (A, B, C) of positive integers satisfy A * B + C = n?

Input

One positive integer n (2n108).

Output

Print the required number of tuples.

Time limit 2 seconds
Memory limit 128 MiB
Input example #1
3
Output example #1
3
Input example #2
11
Output example #2
27