#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
long long  n, phi[1000005];

int main()
{
    in >> n;
    for(int i=1; i<=n; i++)
    phi[i] = i-1;

    for(int i=1; i<=n; i++)
        for(int j=2*i; j<=n; j+=i)
        phi[j]-=phi[i];
long  sum =0;

    for(int i=1; i<=n; i++)
       sum += phi[i] *2;
       out << sum+1;

    return 0;
}