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.Scanner;

public class Main {

	public static void main(String[] args) {
		int ans = 0;
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		
		for(int i=1;i<=n;i++) {
			for(int j=1;j<=n;j++) {
				if(i*j < n) {
					ans++;
				}
				else {
					break;
				}
			}
		}
		
		System.out.println(ans);
	}
}
