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.*;
import java.io.*;
import java.math.*;

public class Main{



  public static OutputStream out=new BufferedOutputStream(System.out);
  static Scanner sc=new Scanner(System.in);
  static long MOD=1000000007l;
  static int INF=10000000;
  static int[] rr=new int[]{1, 0, -1, 0};                                 //rook row move
  static int[] rc=new int[]{0, 1, 0, -1};                                 //rook col move

  //nl-->neew line; //l-->line;  //arp-->array print;  //arpnl-->array print new line
  public static void nl(Object o) throws IOException{out.write((o+"\n").getBytes()); }
  public static void l(Object o) throws IOException{out.write((o+"").getBytes());}
  public static void arp(int[] o) throws IOException{for(int i=0;i<o.length;i++) out.write((o[i]+" ").getBytes()); out.write(("\n").getBytes());}
  public static void arpnl(int[] o) throws IOException{for(int i=0;i<o.length;i++) out.write((o[i]+"\n").getBytes());}
  public static void scanl(long[] a,int n) {for(int i=0;i<n;i++) a[i]=sc.nextLong();}
  public static void scani(int[] a,int n) {for(int i=0;i<n;i++) a[i]=sc.nextInt();}
  public static void scan2D(int[][] a,int n,int m) {for(int i=0;i<n;i++) for(int j=0;j<m;j++) a[i][j]=sc.nextInt();}
  //static variables

  //


  public static void main(String[] args) throws IOException{
    long sttm=System.currentTimeMillis();
    long mod=1000000007l;

    // int k=sc.nextInt();
    int k=1;
    while(k-->0){
        solve();
    }

    out.flush();
  }

  public static void solve() throws IOException{
      int n=sc.nextInt();
      long ans=0;
      for(int i=1;i<n;i++){
          int alpha=(n-1)/i;
          ans+=alpha;
      }
      nl(ans);
  }

}

class Pair{
  int x; int y;
  Pair(int x,int y){
    this.x=x;
    this.y=y;
  }
}
