#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int N, V[1000010];
long long sol;
int main()
{
    f>> N;
    for (int i=2; i<=N; i++) V[i] = i - 1;
    for (int i=2; i<=N; i++)
    {
        for (int j=(i << 1); j<=N; j+=i)
            V[j] -= V[i];
        sol += V[i];
    }
    g << sol * 2 + 1 << '\n';
    g.close();
    return 0;
}