#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int sol;
int main() {
	const int max = 100001;
	int phi[max];
	int N;
		fin >> N;
	for (int i = 1; i <= N; ++i) {
		phi[i] = i - 1;
	}
	for (int i = 2; i <= N; ++i) {
		sol += phi[i];
		for (int j = 2 * i; j <= N; j += i) {
			phi[j] -= phi[i];
			
		}
	}
	
	fout << 2 * sol + 1 << '\n';
}