using namespace std;
#include<fstream>
unsigned int i,j,N,v[1000005];
long long contor=0;

int main()
{
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");
	fin>>N;
	for(i=1; i<=N; i++)
		v[i]=i-1;
	for(i=2; i<=N; i++)
		{	contor=contor+v[i];
			for(j=2*i; j<=N; j+=i)
			v[j]-=v[i];}
		contor=contor*2+1;
		fout<<contor;
	return 0;
}