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.io.*;
import java.util.*;

class Main {
	public static void main(String[] $) {
		new Main().run();
	}
	
	void run() {
		Scanner sc=new Scanner(System.in);
		long N=sc.nextLong();
		long ans=0;
		for (long a=1;a<N;++a) {
			long b=N/a;
			if (a*b==N) --b;
			ans+=b;
		}
		System.out.println(ans);
	}
	
	void tr(Object...objects) {System.out.println(Arrays.deepToString(objects));}
}
