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.Scanner;

/**
 * Created by enpingkuang on 2020/9/19 7:53 下午
 */
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        long dp[] = new long[1000006];
        for(int i = 1;i<1000006;i++){
            for(int j = 1;j*i<1000006;j++){
                dp[j*i]++;
            }
        }
        if(n== 1){
            System.out.println(1);
        }else{
            long ans = 1;
            for(int i = 2;i<n;i++){
                ans += dp[i];
            }
            System.out.println(ans);
        }

    }
}
