#include    <fstream>

using namespace std;

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

#define LL long long
#define VECTOR_MAX 1000000

LL N, counter;
LL arr[VECTOR_MAX];

int main() {
    fin >> N;

    for (int i = 2; i <= N; i++)
        arr[i] = i - 1;

    for (int i = 2; i <= N / 2; i++)
        for (int j = 2 * i; j <= N; j += i)
            arr[j] -= arr[i];

    for (int i = 2; i <= N; i++)
        counter += arr[i];

    fout << counter * 2 + 1;
}