#include <iostream>
#include <fstream>

using namespace std;

int main()
{
	int n, i, j;
	long numere = 0 ;
	int vec[1000000];
	
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");

	fin >> n;

	for ( i = 1; i <= n; i++ )
		vec[i] = i-1;

	for ( i = 1; i <= n; i++ )
	{
		for ( j = 2 * i ; j<=n; j += i)
			vec[j] -= vec[i];
		numere += vec[i];
	}

	fout << numere * 2 + 1;

	fin.close();
	fout.close();

	return 0;
}