/* package codechef; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
public class Main
{
    static int MAX = 1000001; 
    static int factor[]; 
  
    // function to generate all prime 
    // factors of numbers from 1 to 10^6 
    static void generatePrimeFactors() 
    { 
        factor[1] = 1; 
  
        // Initializes all the positions with 
        // their value. 
        for (int i = 2; i < MAX; i++) 
            factor[i] = i; 
  
        // Initializes all multiples of 2 with 2 
        for (int i = 4; i < MAX; i += 2) 
            factor[i] = 2; 
  
        // A modified version of Sieve of 
        // Eratosthenes to store the 
        // smallest prime factor that 
        // divides every number. 
        for (int i = 3; i * i < MAX; i++) { 
            // check if it has no prime factor. 
            if (factor[i] == i) { 
                // Initializes of j starting from i*i 
                for (int j = i * i; j < MAX; j += i) { 
                    // if it has no prime factor 
                    // before, then stores the 
                    // smallest prime divisor 
                    if (factor[j] == j) 
                        factor[j] = i; 
                } 
            } 
        } 
    } 
  
    // function to calculate number of factors 
    static int calculateNoOFactors(int n) 
    { 
        if (n == 1) 
            return 1; 
  
        int ans = 1; 
  
        // stores the smallest prime number 
        // that divides n 
        int dup = factor[n]; 
  
        // stores the count of number of times 
        // a prime number divides n. 
        int c = 1; 
  
         
        int j = n / factor[n]; 
  
        // false when prime factorization is done 
        while (j != 1) { 
             
            if (factor[j] == dup) 
                c += 1; 
  
            
            else { 
                dup = factor[j]; 
                ans = ans * (c + 1); 
                c = 1; 
            } 
  
            // prime factorizes a number 
            j = j / factor[j]; 
        } 
  
        // for the last prime factor 
        ans = ans * (c + 1); 
  
        return ans; 
    } 
    
	public static void main (String[] args) throws java.lang.Exception
	{
	    factor = new int[MAX]; 
        factor[0] = 0; 
      // prime factorizes a number 
         generatePrimeFactors(); 
      // prime factorizes a number 
	    Scanner sc=new Scanner(System.in);
	    int n=sc.nextInt();
      // prime factorizes a number 
	    long sum=0;
	    for(int i=1;i<n;i++)
	    sum+=(long)calculateNoOFactors(i);
	    System.out.println(sum);
	        
	}
}