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.util.*;
public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc= new Scanner(System.in);
		
		int  N= sc.nextInt();
		sc.close();
		int ans=0;		
		for(int a= 1;a<N;a++){
			for(int b= 1; a*b<N;b++){
				ans++;
			}
		}
		
		System.out.println(ans);
		
		
	}

}
