#include "bits/stdc++.h"
#include "ext/pb_ds/assoc_container.hpp"
#include "ext/pb_ds/tree_policy.hpp"
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
using namespace std;
using namespace __gnu_pbds;
#define int long long int
#define pb push_back
#define vec vector<int>
#define fo(i, n) for (int i = 0; i < n; i++)
#define foo(i, a, b) for (int i = a; i < b; i++)
#define mp make_pair
#define deb(x) cout << #x << " --> " << x << endl;
#define deb1a(v)                  \
    cout << #v << "--->" << endl; \
    for (auto it : v)             \
        cout << it << " ";        \
    cout << endl;
#define deb2a(v)                  \
    cout << #v << "--->" << endl; \
    for (auto it : v)             \
    {                             \
        for (auto it1 : it)       \
        {                         \
            cout << it1 << " ";   \
        }                         \
        cout << endl;             \
    }
#define deb3a(v)                               \
    cout << #v << "-->" << endl;               \
    for (auto it : v)                          \
    {                                          \
        cout << it.fi << " " << it.se << endl; \
    }
#define mod 1000000007
#define so(v) sort(v.begin(), v.end())
#define fi first
#define se second
#define db1(x) cout << #x << "=" << x << endl
#define db2(x, y) cout << #x << "=" << x << "," << #y << "=" << y << endl
#define db3(x, y, z) cout << #x << "=" << x << "," << #y << "=" << y << "," << #z << "=" << z << endl
int power(int x, unsigned int y, int p)
{
    int res = 1;
    x = x % p;
    while (y > 0)
    {
        if (y & 1)
            res = (res * x) % p;
        y = y >> 1;
        x = (x * x) % p;
    }
    return res;
}
int mI(int a, int m)
{
    return power(a, m - 2, m);
}
vector<vector<int>> dir = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}, {1, 1}, {1, -1}, {-1, 1}, {-1, -1}};
#define double long double

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()
{
    int n;
    cin >> n;
    int ans = 0;
    generatePrimeFactors();
    foo(i,1,n){
        ans += calculateNoOFactors(i);
    }
    cout << ans << "\n";
}


int32_t main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    srand(time(0));

    // FILE *fin = freopen("ip.txt","r",stdin);
    // FILE *fout = freopen("op.txt","w",stdout);
    int t = 1, nn = 1;
    //cin >> t;
    while (t--)
    {
        // cout << "Case #" << nn << ":"
        //      << " ";
        // nn++;

        solve();
    }
}

Measured memory_bytes: 11456