#include <fstream>

using namespace std;

int v[1000001];
int n, i, j;
long long s;

int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f >> n;
    for(i = 2; i <= n; i++)
    {
        v[i] += i - 1;
        for(j = i + i; j <= n; j += i)
            v[j] -= v[i];
        s += v[i];
    }
    s = s * 2 + 1;
    g << s;
    f.close();
    g.close();
    return 0;
}