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.math.*;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;

public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    long count = 0;
    for (long i = 1, len = (long) Math.floor(Math.sqrt(n)); i <= len; i++) {
      for (long j = i, lenj = n / i; j <= lenj; j++) {
        if (i * j == n) {
          continue;
        }
        if (i == j) {
          count++;
        } else {
          count += 2;
        }
      }
    }
    System.out.println(count);
  }
}
