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.BigDecimal;
import java.math.MathContext;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int count = 0;


		BigDecimal delta = new BigDecimal("0.0000001");
		BigDecimal bn = new BigDecimal(n);

		for (int i = 1; i < n; i++) {

			BigDecimal sub = bn.divide(new BigDecimal(i).add(delta),MathContext.DECIMAL128);
			count += sub.intValue();
		}
		System.out.println(count);

	}
}
