#include <iostream>
#include <fstream>

using namespace std;

ifstream fin ("fractii.in");
ofstream fout ("fractii.out");

#define MAXN 1000050

int N, X[MAXN];

int main()
{
    fin >N;

    for (int i = 2; i <= N; ++i)
		X[i] = i - 1;

	long long solution = 0;
	for (int i = 2; i <= N; ++i)
	{
		solution += X[i];
        for (int j = i + i; j <= N; j += i)
            X[j] -= X[i];
	}

	solution *= 2;

	fout <<solution + 1 <<'\n';

    return 0;
}