Number of divisors

#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <map>
#include <set>

//#include "BigInt.h"

using namespace std;

#define ll long long
#define ull unsigned long long
const ll INF = 999999999999999999;
const double PI = acos(-1.0);

void stop()
{
#ifndef ONLINE_JUDGE
    system("pause");
#endif
    exit(0);
}



int main()
{
    //freopen(".in", "r", stdin);
    //freopen(".out", "w", stdout);
    ios::sync_with_stdio(false);

    ll n;
    cin >> n;
    ll res = 0;
    for (ll i = 1; i*i <= n; i++)
    {
        res += n / i;
    }
    res *= 2;
    res -= (ll)sqrt(n)*(ll)sqrt(n);
    cout << res;

    stop();
}