#include "fstream"
#include "iostream"
using namespace std;
int main(){
	ifstream in;
	in.open("fractii.in");
	if (in){
		ofstream out;
		out.open("fractii.out");
		if (out){
			long n;
			in >> n;
			long phi[1000004];
			for (int i = 1; i <= n ; i++){
				phi[i] = i - 1;
			}

			long s = 0;
			for (long i = 2; i <= n; i++){
				s += phi[i];
				for (long j = 2 * i; j <= n; j += i){
					phi[j] -= phi[i];
				}
			}
			out << 2*s+1;
			out.close();
			in.close();
		}
	}
	return 0;
}