#include <bits/stdc++.h>
    #include <math.h>
 
    using namespace std;
    typedef long long ll;
    typedef unsigned long long ull;
    # define M_PI  3.14159265358979323846
 
 
    const int M=1e9+7;
    long long mod(long long x){
        return ((x%M + M)%M);
    }
    long long add(long long a, long long b){
        return mod(mod(a)+mod(b));
    }
    long long mul(long long a, long long b){
        return mod(mod(a)*mod(b));
    }
 
    ll modPow(ll a, ll b){
        if(b==0)
            return 1LL;
        if(b==1)
            return a%M;
        ll res=1;
        while(b){
            if(b%2==1)
                res=mul(res,a);
            a=mul(a,a);
            b=b/2;
        }
        return res;
    }

const int MAX = 1000001; 
  
// array to store prime factors 
int factor[MAX] = { 0 }; 
  
// function to generate all prime factors 
// of numbers from 1 to 10^6 
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 
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; 
  
    // reduces to the next number after prime 
    // factorization of n 
    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; 
} 
 
    void solve (){
        ll total=0;
        ll n;
        cin>>n;
        generatePrimeFactors(); 
        for(int i=1;i<n;i++){
            ll k=calculateNoOFactors(i);
            total+=k;
        }
        cout<<total;
    }
    int main(){
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout.tie(0);
        cout<<fixed;
        cout<<setprecision(10);
//        freopen("timber_input.txt", "r", stdin);
//        freopen("timber_output.txt", "w", stdout);
        int t=1;
        // cin>>t;
        for(int i=1;i<=t;i++){
//            cout<<"Case #"<<i<<": ";
            solve();
        }
        return 0;
    }

Measured memory_bytes: 7556