#include<fstream.h>

int *a=new int [1000001];

int main()
{
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");

	long n;

	fin>>n;

	long i,j;

	for (i=1;i<=n;i++)
	a[i]=i-1;

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

	long sum=0;

	for (i=2;i<=n;i++)
		sum+=a[i];

	fout<<sum*2+1;

	fin.close();
	fout.close();
	return 0;
}