#define nmax 1000001
#define _CRT_SECURE_NO_WARNINGS
#include<cstdio>
#include<math.h>

int n;
int v[nmax];

int main(){
	freopen("fractii.in", "r", stdin);
	freopen("fractii.out", "w", stdout);
	scanf("%d", &n);	
	long long nr = 0;
	for (int i = 1; i <=n; ++i) v[i] = i - 1;
	for (int i = 2; i <= n; ++i){
		for (int j = 2*i; j <= n; j += i)
			v[j] -= v[i];
		nr += v[i];
	}
	printf("%lld", 2*nr + 1 );
	return 0;
}