#include <cstdio>
#define nmax 1000000
using namespace std;
FILE *f1, *f2;

long int n,i,j;
long int v[nmax],s=0;
int main()
{
	f1 = freopen("fractii.in", "r", stdin);
	scanf("%i", &n);
	fclose(f1);
	
	for(i=1;i<=n;i++) v[i] = i-1;
	for(i = 2;i<=(n/2+1); i++)
		for(j = i+i; j<=n;j+=i)
			v[j] -= v[i];
	for(i=2;i<=n;i++)
		s+= v[i];
	
	s*=2;
	s++;
	f2 = freopen("fractii.out", "w", stdout);
	printf("%i\n", s);
	fclose(f2);
	return 0;
}