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 {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int ab;
        int yakusu[] = new int[n];
        yakusu[0] = 0;
        for(int i = 1; i < n; i++){
            for(int j = 1; i * j < n; j++){
                yakusu[i * j] += 1;
            }
        }
        int cnt = 0;
        int yakusu_sum[] = new int[n];
        yakusu_sum[0] = 0;
        for(int i = 1; i < n; i++){
            cnt += yakusu[i];
            yakusu_sum[i] = cnt;
        }
        
        System.out.println(yakusu_sum[n - 1]);
    }
}
