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(final String[] args) {
    	Scanner s = new Scanner(System.in);
    	int n = s.nextInt();
    	int cnt = 0;
    	for (int a = 1; a < n; a++) {
    		for (int b = 1; b < n; b++) {
    			if (a * b > n) {
    				break;
    			}
    			int c = n - a * b;
    			if (c > 0) {
    				cnt++;
    			}
    		}
    	}
    	System.out.println(cnt);
    }
}