/* 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; 
  
         
        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 (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]; 
  
        int c = 1; 
  
        int j = n / factor[n]; 
  
        // false when prime factorization is done 
        while (j != 1) { 
            // if the same prime number is dividing n, 
            // then we increase the count 
            if (factor[j] == dup) 
                c += 1; 
  
            /* if its a new prime factor that is  
               factorizing n, then we again set c=1  
               and change dup to the new prime factor, 
               and apply the formula explained  
               above. */
            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
	{
      /* if its a new prime factor that is  
               factorizing n, then we again set c=1  
               and change dup to the new prime factor, 
               and apply the formula explained  
               above. */
	    factor = new int[MAX]; 
        factor[0] = 0; 
         generatePrimeFactors(); 
	    Scanner syed=new Scanner(System.in);
	    int n=syed.nextInt();
	    long sum=0;
	    for(int i=1;i<n;i++)
	    sum+=(long)calculateNoOFactors(i);
	    System.out.println(sum);
	        
	}
}