#include <cstdio>
#include <vector>
using namespace std;

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

	int n,anz=0,a;
	float tot;
	scanf ("%d", &n);
	
	for (int i=2;i<=n;i++)
	{
		tot=i;
		a=i;
		for (int j=2;j<=n;j++)
			if (a%j==0)
			{
				tot*=1.0-1.0/j;
				while (a%j==0)				
					a/=j;
			}
		anz+=(int)tot;
	}
			

		
	printf ("%d \n", anz*2+1);
}