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