#include<fstream>
#include<cmath>
using namespace std;

const int N = 1000001;
int d[N];

int main()
{
	int n,i,j,s,p;
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");
	fin>>n;
	s = n*n;
	for (i=2;i<=n;i++)
	{
		if (d[i]==0)
		{
			p=1;
			for (j=i;j<=n;j+=i)
			{
				if (d[j]==0)
					d[j]=1;
				if (j%((int)pow((double)i,(double)p+1))==0)
					p++;
				d[j]*=p+1;
			}
		}
		s-=2*d[i]-3;
	}
	fout<<s<<'\n';
	fin.close();
	fout.close();
	return 0;
}