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 <iostream>
#include<math.h>
#include <stdio.h>
using namespace std;
#include <string>
#include <vector>
int main(void) {
    int n;
    int a;
    int count=1;
    cin >>n;
    for(int i=1;i<n;i++){
        a=i;
        for(int i=0;i<n/a;i++){
            count+=1;
            }
    
    }
    cout<<count;
}