#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int 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 long  sum =0;

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

    return 0;
}