#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 (long long i = 2; i * i <= n; i++) {
        if (n % i == 0) return 0;
    }
    return 1;
}

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

    long long cnt_pairs = 0;
    for (long long i = 2; i <= n; i++) {
        if (isPrime(i)) {
            long long prime_divs = n / i;
            cnt_pairs += prime_divs * (prime_divs - 1);
        }
    }

    long long sol = 1 + n * (n - 1) - cnt_pairs;
    out << sol;

    return 0;
}