#include <fstream>
#include <algorithm>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <iostream>
#include <string.h>
#include <vector>
using namespace std;

int v[1000001];
long long suma;

int main()
{
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    
	int n, i, j;
    
	//Read
	fin>>n;
    
	
	//Compute
	for(i=1; i<=n; i++)
        v[i] = i-1;
    for(i=2; i<=n; i++)
        for(j=2*i; j<=n; j+=i)
            v[j] -= v[i];
    for(i=1; i<=n; i++)
        suma += v[i]*2;
    
	
	//Print
	fout<<suma+1;
}