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.math.BigInteger;
import java.util.Scanner;

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();
		BigInteger cnt = BigInteger.ZERO;
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= n; j++) {
				if (i * j < n) {
					cnt = cnt.add(BigInteger.ONE);
				} else {
					break;
				}
			}
		}
		System.out.println(cnt);
	}
}
