#include<fstream>
int phi(long long int n) {
	long long int result = n;
	for (int i = 2; i * i <= n; i++) {
		if (n % i == 0) {
			while (n % i == 0)
				n /= i;
			result -= result / i;
		}
	}
	if (n > 1)
		result -= result / n;
	return result;
}

int main() {
	FILE *i, *o;
	long long int n, result = 1;
	i = fopen("fractii.in", "r");
	fscanf(i, "%d", &n);
	o = fopen("fractii.out", "w");
	for (int i = 2; i <= n; i++)
		result += 2 * phi(i);
	fprintf(o, "%d\n", result);
	fclose(i);
	fclose(o);
	return 0;
}