#include<fstream>
#define NrP 1000 
using namespace std;

int prime[NrP],phi[1000000];

void GetPrimes(int n)
{
	int i,j;
	
	for(i=2;i<=n;i++)
		if(prime[i] == 0)
			for(j = 2*i;j<=n;j+=i)
				p[j] = 1;
}

int main()
{
	int i,j,n,s = 0;
	
	ifstream fin("fractii.in");
	ofstream fout("fractii.out");
	
	fin>>n;		

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

	fout<<2*s - 1<<"\n";
	
return 0;
}