#include <bits/stdc++.h>

using namespace std;

ifstream in("fractii.in");
ofstream out("fractii.out");

bool isPrime(int n) {
    if (n < 2) return 0;
    for (int i = 2; i * i <= n; i++) {
        if (n % i == 0) return 0;
    }
    return 1;
}

int main() {
    int n;
    in >> n;

    int odd = n / 2 + n % 2;
    int even = n / 2;
    
    int sol_odd = (odd - 1) * (odd - 1 + even);
    int sol_even = even * odd;

    int cnt_pairs = 0;
    for (int i = 3; i <= n; i++) {
        if (isPrime(i)) {
            int prime_divs = n / i;
            cnt_pairs += prime_divs * (prime_divs - 1);
        }
    }

    int sol = n + sol_odd + sol_even - cnt_pairs;

    out << sol;

    return 0;
}