#include <fstream>
#include <vector>

using namespace std;

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

int main() {

	int N;
	fin >> N;

	vector <int> TotF(1 + N);
	for (int no = 2; no <= N; ++no)
		TotF[no] = no - 1;

	for (int no = 2; no <= N; ++no)
		for (int mult = 2 * no; mult <= N; mult += no)
			TotF[mult] -= TotF[no];

	long long sum = 0;
	for (int no = 2; no <= N; ++no)
		sum += TotF[no];

	fout << 2 * sum + 1;
}