#include<cstdio>
using namespace std;
long long n,i,j,a=0,x[1000001];
void read()
{
	freopen("fractii.in","r",stdin);
	freopen("fractii.out","w",stdout);
	scanf("%lld",&n);
}

void rez()
{

	for(i=2;i<=n;i++) 
		x[i]=i-1;
	for(i=2;i<=n;i++)
	{
		a=a+x[i];
		for(j=2*i;j<=n;j=j+i) 
			x[j]=x[j]-x[i];
	}

	printf("%lld\n",a*2+1);	
}

int main()
{
	read();
	rez();
	return 0;
}