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.*;

public class Main{ //クラス名はMain
    public static void main(String[] args) {
			
			Scanner sc = new Scanner(System.in);
			long n = Long.parseLong(sc.next());
			
			/*--------------------------------*/
			//入力
			//int n = 5;
			long ans = 0;
			long c = 0;
			for(long a =1;a<n;a++){
				for(long b = a;a*b<n;b++){
                  ans++;
				  if(a==b){
                    c++;
                  }
				}
			}

			System.out.println((ans*2)-c);
    }
}

