#include <iostream>
#include <vector>
#include <cmath>

std::size_t solve(std::size_t n) {
    std::vector<bool> is_square_free(n + 1, true);
    for (std::size_t i = 2; i * i <= n; ++i) {
        if (!is_square_free[i * i])
            continue;
        for (std::size_t j = i * i; j <= n; j += i * i)
            is_square_free[j] = false;
    }
    
    std::size_t ans = 0;
    for (std::size_t k = 1; k <= n; ++k) {
        if (is_square_free[k]) {
            std::size_t tmp = std::floor(std::sqrt((double) n / k));
            ans += tmp * tmp;
        }
    }
    return ans;
}

int main() {
    std::size_t n;
    std::cin >> n;
    std::cout << solve(n) << std::endl;
}