#include <iostream>
#include <fstream>
#include <vector>
#define MAX_SIZE 1000001
using namespace std;

int phi[MAX_SIZE];

int main() {
	ofstream out;
	ifstream in;
	long long n, count = 0;

	in.open("fractii.in");
	out.open("fractii.out");
	in >> n;
	
    for (int i = 1; i <= n; i ++)
        phi[i] = i - 1;

    for (int i = 2; i <= n; i ++)
        for (int j = 2 * i; j <= n; j += i)
            phi[j] -= phi[i];

    for (int i = 2; i <= n; i ++)
        count += phi[i];
    count *= 2;
    count ++;
    //count += 2 * n + 1;

	out << count << endl;

    return 0;
}