#include <stdio.h>
#include <vector>
#include <algorithm>
#include <math.h>
 
using namespace std;

#define MAXN 1000001
#define ll long long int

int totient[MAXN];

int main() {
	freopen("fractii.in", "r", stdin);
	freopen("fractii.out", "w", stdout);

	int n;

	scanf("%d", &n);

	for (int i = 1; i <= n; ++i) {
		totient[i] = i - 1;
	}

	ll sum = 0;

	for (int i = 2; i <= n; ++i) {
		for (int j = i + i; j <= n; j += i) {
			totient[j] -= totient[i];
		}
		sum += totient[i];
	}

	printf("%lld", sum * 2 + 1);

	return 0;
}