using namespace std;
#include<fstream>
ifstream fin("fractii.in");
ofstream fout("fractii.out");
unsigned int i,j,N,contor;
char v[1000005];

int main()
{	contor=0;
	fin>>N;
	for(i=1; i<=N; i++)
		v[i]=i-1;
	for(i=2; i<=N; i++)
		{	contor=contor+v[i];
			for(j=i+i; j<=N; j=j+i)
			v[j]=v[j]-v[i];}
		contor=contor*2+1;
		fout<<contor;
	return 0;
}