#include <fstream>
using namespace std;
long long int sumatotiene;
ifstream f("fractii.in");
ofstream g("fractii.out");
int fi(long long int n) 
{ 
       long long int result = n; 
       for(int i=2;i*i <= n;i++) 
       { 
         if (n % i == 0) result -= result / i; 
         while (n % i == 0) n /= i; 
       } 
       if (n > 1) result -= result / n; 
       return result; 
} 
     
int main(){
	int n;
	f>>n;
	for(int i = 2; i <= n; i++){
		sumatotiene += fi(i);
	}
	long long int final = 1 + (2*sumatotiene);
	g << final;
	return 0;
}