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.*;
import java.io.*;
import java.math.BigInteger;
 
public class Main {
	public static long mod = 1000000007;
	
	
	public static void main(String[] args) {
	Scanner s = new Scanner(System.in);
	int N = s.nextInt();
	int sum = 0;
	for(int i = 1; i < N; i++){
		sum += (N-1)/i;
	}

	System.out.println(sum);
	
	
	
    
  }
}