#include <iostream>
#include <cmath>

long long n, h, contadivisori;

void contadiv(long long  x) {
    contadivisori = 0;
    long long  y = 1;
    h = 1;
    while (y <= static_cast<int64_t>(std::trunc(std::sqrt(x)))) {
        if (x % y == 0) {
            if (y != x / y) 
                h += 2;
            else 
                h += 1;
        }
        y++;
    }
    contadivisori = h - 1;  
}

long long  compute(long long  x) { 
    long long  i, somma = 0;
    for (i = 1; i <= n; i++) {
        contadiv(i);
        somma += contadivisori;
    }
    return somma;
}

int main() {
    std::cin >> n;
    std::cout << compute(n) << std::endl;
    return 0;
}