#include <bits/stdc++.h>
using namespace std;

#define fastio ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL)
#define lli long long int
#define rep(i,n,z) for(int i=z;i<n;i++)
#define rrep(i,z) for(int i=z;i>=0;i--)
#define nl cout<<endl
#define vi vector<int>
#define vlli vector<long long int>
#define vvi vector<vector<int>>
#define vvlli vector<vlli>
#define umap unordered_map
#define pb push_back
#define mp make_pair
#define ss second
#define ff first
#define ipair pair <int,int>
#define llipair pair <lli,lli>
#define pq priority_queue
#define displaymatrix(a,m,n) for(int i=0;i<m;i++){for(int j=0;j<n;j++)cout<<a[i][j]<<" ";cout<<endl;}
#define printarray(a,n) for(int i=0;i<n;i++){cout<<a[i]<<" ";}nl;
#define vinput(a,n) vlli a(n);rep(i,n,0)cin>>a[i]
#define ainput(a,n) rep(i,n,0)cin>>a[i]
#define SO(a) sort(a.begin(),a.end())
#define all(x) (x).begin(),(x).end()
#define SOP(a,comp) sort(a.begin(),a.end(),comp)
#define inf INT_MAX
#define endl '\n'


vector<int> vis;
vector<vector<int>> adj;
vector<long double > dis;
lli val;
lli paths;

const int MAX = 1000001; 
int factor[MAX] = { 0 }; 


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; 
            } 
        } 
    } 
} 

int calculateNoOFactors(int n) 
{ 
    if (n == 1) 
        return 1; 
  
    int ans = 1; 

    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; 
        } 
        j = j / factor[j]; 
    } 
    ans = ans * (c + 1); 
    return ans; 
} 



void solve(){
    int n;
    cin>>n;
    lli ans = 0;
    int dp [n+1];
    memset(dp, 0, sizeof(dp));
    generatePrimeFactors();
    for(int i = 1;i< n;i++){
        dp[i] = calculateNoOFactors(i);
        int temp = sqrt(i);
        // if(temp * temp == i&& i > 1) dp[i]--;
    }
    for(int i = 1;i< n;i++)ans+= dp[i];
    // printarray(dp, n+1);
    cout<<ans<<endl;
}


int main()
{
    fastio;
    int t;
    t = 1;
    // cin>>t;
    while(t--)solve();

}

Measured memory_bytes: 11440