#include <iostream>
#include <fstream>
#include <bitset>

const char IN[] = "fractii.in", OUT[] = "fractii.out";
const int NMAX = 1000000;

using namespace std;

int N;
int parts[NMAX];
int uses[NMAX];

long long gen() {
	long long nr = 0;
	for (int i = 2; i <= N; ++i) {
		parts[i] += i - 1;
		for (int j = i + i; j <= N; j += i)
			parts[j] -= parts[i];
		nr += parts[i];
	}
	return nr * 2 + 1;
}

int main() 
{
	fscanf(fopen(IN, "r"), "%d", &N);
	fprintf(fopen(OUT, "w"), "%lld\n", gen());
	return 0;
}