201130: [AtCoder]ARC113 A - A*B*C
Memory Limit:1024 MB
Time Limit:2 S
Judge Style:Text Compare
Creator:
Submit:0
Solved:0
Description
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