#include <fstream>
#define MaxN 1000001
using namespace std;
fstream fin ("fractii.in", ios::in);
fstream fout ("fractii.out", ios::out);
int N;
int phi[MaxN];
int s;
int main(){
	
	fin>>N;
	
	for (int i = 1; i <= N; ++i)
		phi[i] = i-1;
	for (int i = 2; i <= N; ++i)
		for (int j = 2*i; j <= N; j += i)
			phi[j] -= phi[i];
	for (int i = 1; i <= N; ++i)
		s += phi[i];
	fout<<2*s +1;
};