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.

Examples

Input

3


Output

3


Input

100


Output

473


Input

1000000


Output

13969985
import java.awt.*;
import java.io.*;
import java.util.*;
 
public class Main {
	Scanner sc = new Scanner(System.in);
	public static void main(String[] args){
		new Main();
	}
	public Main(){
		new TestB().doIt();
	}
	class TestB{
		void doIt() {
			int N = sc.nextInt();
			int cnt = 0;
			for(int i = 1;i < N;i++) {
				cnt = cnt + ((N - 1) / i);
			}
			System.out.println(cnt);
		}
	}
}