#include <iostream>
#include <fstream>

using namespace std;

long long  v[1000005];

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

	int n, i,j;
	f >> n;
	long long s = 0;
	for (i = 2; i <= n; ++i) {
		v[i] = i - 1;
	}

	for (i = 2; i <= n; ++i) {
		for (j = 2 * i; j <= n; j += i){
			v[j] -= v[i];
		}
		s += v[i];
	}

	s = s * 2 + 1;

	g << s;

	f.close();
	g.close();
	return 0;
}