#include <stdio.h>
#include <stdlib.h>


int indEuler(int n)
{
    int i, t = n;
	for (i = 2; i*i <= n; i++)
	{
		if (t%i == 0)
		{
			while (n%i == 0) n /= i;
			t = (t / i)*(i - 1);
		}
	}
	if (n != 1) t = t / n*(n - 1);
	return t;
}

int main()
{
	int n, i, nr = 0;
	FILE *f = fopen("fractii.in", "r"), *g = fopen("fractii.out", "w");
	fscanf(f, "%d", &n);
	for (i = 1; i <= n; i++)
	{
		if (i==1)
		   nr += indEuler(i);
		else nr += 2 * indEuler(i);
	}
	fprintf(g,"%d ", nr);
	fclose(f);fclose(g);
	return 0;
}