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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

// Born Sinner
// old but im not that old
// fuck all you hoes get a grip
import java.util.*;
import java.lang.*;
import java.io.*;
import java.math.BigInteger;

public class Main
{
    static class FastReader{
        BufferedReader br;
        StringTokenizer st;
        public FastReader(){
            br = new BufferedReader(new InputStreamReader(System.in));
        }
        String next(){
            while(st == null || !st.hasMoreElements()){
                try{
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e){
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }
        int nextInt(){
            return Integer.parseInt(next());
        }
        long nextLong(){
            return Long.parseLong(next());
        }
        double nextDouble(){
            return Double.parseDouble(next());
        }
        String nextLine(){
            String str = "";
            try{
                str = br.readLine();
            } catch (Exception e){
                e.printStackTrace();
            }
            return str;
        }
    }
    static int modPower(int x, int y, int mod){
        int res = 1;
        x %= mod;
        if(x==0) return 0;
        while(y>0){
            if(y%2==1){
                res = (res*x)%mod;
            }
            y = y>>1;
            x = (x*x)%mod;
        }
        return res;
    }
    static class pair<T1, T2>{
        T1 first;
        T2 second;
        pair(T1 first, T2 second){
            this.first = first;
            this.second = second;
        }
    }
    static int gcd(int a, int b){
        if(b == 0) return a;
        return gcd(b, a%b);
    }

    public static void main (String[] args) throws java.lang.Exception
    {
        FastReader in = new FastReader();
        int n = in.nextInt();
        n--;
        int ans = 0;
        for(int i = 1; i <= n; i++) {
            ans += n/i;
        }
        System.out.println(ans);
    }
}