#include <fstream>

using namespace std;

int main()
{
    ifstream fin("fractii.in");
    ofstream fout("fractii.out");
    int n;
    fin >> n;
    int a[n + 2];
    int i, j;
    unsigned long long nrf = 0;
    for(i = 2; i <= n; i++)
        a[i] = i - 1;
    for(i = 2; i <= n; i++)
    {
        nrf += a[i];
        for(j = 2 * i; j <= n;j += i)
            a[j] -= a[i];
    }
    fout << nrf * 2 + 1;
    return 0;
}