#include <iostream>
#include <fstream>

using namespace std;

int v[1000000];

int main()
{
	int n;
	cin >> n;
	for (int i = 1; i <= n; i++)v[i] = i - 1;
	long long cnt = 0;
	for (int i = 2; i <= n; i++)
	{
		for (int j = i * 2; j <= n; j += i)
		{
			v[j] -= v[i];
		}
	}

	for (int i = 1; i <= n; i++)
		cnt += v[i];
	cout << cnt * 2 + 1;


}