#include <fstream>
#define int long long
using namespace std;
ifstream in ("fractii.in");
ofstream out ("fractii.out");
int euler (int n)
{
    int save = n,sol=n;
    for (int i = 2;i*i<=n;++i)
    {
        int nr = 0;
        while (n%i==0)
            nr++,n/=i;
        if (nr)
            save/=i,save*=i-1;
    }
    if (n>1)
        save/=n,save*=n-1;
    return save;
}
main ()
{
    int n;
    in>>n;
    int s = 0;
    for (int i = 1;i<=n;++i)
        s+=euler(i);
    out<<2*s-1;
}