#include <fstream>
#define NMAX 1000005

using namespace std;

long ciur[NMAX],n;
long long total;

int main()
{
	fstream fin,fout;
	long i,j;
	fin.open("fractii.in",ios::in);
	fout.open("fractii.out",ios::out);

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

	for(i=2;i<=n;i++)
		total+=ciur[i];
	total=total*2+1;

	fout<<total<<'\n';
	fin.close();
	fout.close();
	return 0;
}