#include <fstream>

using namespace std;

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

int erath[1000005];
long long n, ans;

int main() {
    cin >> n;

    for(int i = 1; i <= n; ++i) {
        erath[i] = i - 1;
    }

    for(int i = 2; i <= n / 2 + 1; ++i) {
        for(int j = 2 * i; j <= n; j += i) {
            erath[j] -= erath[i];
        }
    }

    for(int i = 1; i <= n; ++i) {
        ans += erath[i];
    }

    ans *= 2;
    ++ans;
    cout << ans << '\n';
    return 0;
}