#include <fstream>
#include <iostream>

using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

int v[1000005];
int n;
unsigned long long sol;

int main(){
	fin >> n;
	for(int i = 1; i <= n; i++)
		v[i] = i-1;
	for(int i = 2; i <= n; i++)
		for(int j = 2*i; j <= n; j += i)
			v[j] -= v[i];
	for(int i=1;i<=n;i++)
		sol += v[i];
	sol = 2 * sol + 1;
	fout << sol;
	return 0;
}