#include <iostream>
#include <fstream>

using namespace std;

long long int N;

long long phi[1000001];

int main(int argc, char *argv[]) 
{
	ifstream fin("fractii.in");
	fin >> N;
	fin.close();

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

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

	long long s(0);
	for (int i(2); i <= N; ++i)
		s += phi[i];

	ofstream fout("fractii.out");
	fout << 2*s+1 << endl;
	fout.close();

	return 0;
}