#include <iostream>
#include <fstream>
#include <cmath>

using namespace std;

ifstream fi("fractii.in");
ofstream fo("fractii.out");

long long int  indicator(long long int n)
{
	long long int indicator = 1;
	long long int copie = n;
	int i = 2;
	while(n!=1)
	{
		int p = 0;
		long long int number = 1;
		if (n%i == 0)
		{
			while (n%i == 0)
			{
				n /= i;
				p++;
				number *= i;
			}
			indicator *= (i - 1)*number / i;
		}
		i++;
	}
	return indicator;
}

int main()
{
	int n;
	fi >> n;
	int sol = 0;
	for (int i = 1; i<= n;i++)
		sol += indicator(i);
	fo << 2*sol - 1;


	return 0;
}