#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
int numere[1000005];
ofstream out("fractii.out");
long long ciurulluieratostene(int n)
{
	int i,j;
	for (i = 2; i <= n; i++)
	{
		numere[i] = i - 1;
	}
	for (i = 2; i <= n; i++)
	{
		for (j = 2 * i; j <= n; j+=i)
		{
			numere[j] -= numere[i];
		}
	}
	long long total=0;
	for (i = 1; i <= n; i++)total += numere[i];
	total *= 2;
	total++;
	return total;
}
int main()
{
    ifstream in("fractii.in");
	int i,j,curent;
	int n;
	in >> n;
	out << ciurulluieratostene(n);
}