#include <stdio.h>
#define N 1000001

int n;
long long sum;
bool div[N];

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