#include<fstream>
using namespace std;

int phi[1000005];

long long PHI(int N)
{
	long long sol = 0;
	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];
		sol += phi[i];
	}
	return sol*2+1;
}
int main()
{
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");
	int g;
	fin>>g;
	fout<<PHI(g);
	return 0;
}