#include <stdio.h>

#define MAX 1000005

bool s[MAX];
int n;

int gcd (int a, int b) {
	if (b == 0) return a;
	
	return gcd(b, a % b);
}

int count (int x) {
	int c = 0;
	for (int i = x+1; i <= n; ++i) {
		if (gcd(i, x) == 1) ++c;
	}
	
	return c;
}
		 
	
int main (void) {
	freopen("fractii.in", "r", stdin);
	freopen("fractii.out", "w", stdout);
	
	scanf("%d", &n);
	
	int c = 1 + 2*(n-1);
	for (int i = 2; i < n; ++i) {
		c += 2 * count(i);
	}
	
	printf("%d", c);
	
	return 0;
}