#include <fstream>
#define nmax 1000003
using namespace std;

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

int euler[nmax], i, j, n;
long long sol = 0;

int main()
{
    fin >> n;

    for(i = 1; i <= n; i++)
        euler[i] = i - 1;

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

    fout << 2 * sol + 1;

    return 0;
}