#include <fstream>
#define N 1000001

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

int phi[N];

void sieve(int n) {
	int i,j;

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

int main() {
	int i,n,sol = 0;

	f>>n;
	sieve(n);
	for(i = 2; i <= n; i++)
		sol += phi[i];

	g<<(sol<<1)+1;
	return 0;
}