Problem:
Score : 300 points

Problem Statement

Given is a positive integer N.
How many tuples (A,B,C) of positive integers satisfy A \times B + C = N?

Constraints

2 \leq N \leq 10^6

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer.

Sample Input 1

3

Sample Output 1

3

There are 3 tuples of integers that satisfy A \times B + C = 3: (A, B, C) = (1, 1, 2), (1, 2, 1), (2, 1, 1).

Sample Input 2

100

Sample Output 2

473

Sample Input 3

1000000

Sample Output 3

13969985

Solution in C (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<stdio.h>
 
void main(){
  int n,cnt=0;
  scanf("%d",&n);
  for(int i = 1;i<=n;i++){
    for(int j = 1;j<=n;j++){
      for(int z = 0;z<n;z++){
        if(i*j+z == n){
          cnt++;
        }
      }
    }
  }
  printf("%d",cnt);
}