#include <iostream>
#include <fstream>

using namespace std;

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

#define NMax 1000010
#define ll long long

int n;
ll rez;
int phi[NMax];

int main(){
	int i, j;
	fin >> n;
	
	for(i = 1; i <= n; i++) phi[i] = i - 1;
	for(i = 1; i <= n; i++)
		for(j = i + i; j <= n; j += i)
			phi[j] -= phi[i];
	
	for(i = 2; i <= n; i++) rez += phi[i];
	fout << rez * 2 + 1;
}