#include <iostream>
#include <fstream>
using namespace std;

ifstream r("fractii.in");
ofstream w("fractii.out");

int main()
{
	int n, k = 0;
	r >> n;

	int euler[n+1] = {0};

	for (int i = 2; i <= n; i++)
		euler[i] = i - 1;

	for (int i = 2; i <= n; i++) {
		k += euler[i];
		for (int j = 2 * i; j <= n; j += i)
			euler[j] -= euler[i];
	}

	cout << 2 * k + 1;
}