AE00.cpp

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <numeric>
#include <algorithm>
#include <functional>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
//#include <unordered_map>
#include <utility>
#include <cassert>
#include <iomanip>
#include <ctime>
#include <fstream>

using namespace std;

const int me = 200025;

static int uget()
{
    int c;
    while(c = getchar(), isspace(c)) {}
    int n = c - '0';
    while(c = getchar(), isdigit(c)) { n = n * 10 + (c - '0'); }
    return n;
}
template<class T> static void uput(T n)
{
    char s[30];
    int x = 0;
    do { s[x ++]=(n % 10) + '0'; n /= 10; } while(n);
    for(int i = x - 1; i >= 0; i --) putchar(s[i]);
    putchar('\n');
}

int n;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    cin >> n;
    int s = 0;
    for(int i = 1; i <= n; i ++)
        s += max(n / i - i + 1, 0);
    cout << s << endl;
    
    return 0;
}