#include <iostream>
#include <fstream>

using namespace std;

ifstream in ("fractii.in");
ofstream out ("fractii.out");

int euler (int n)
{
    int sol=n;

    int p=3;
    if (n%2==0)
    {
        while (n%2==0)
            n/=2;
        sol/=2;
    }

    while (n!=1)
    {
        if (n%p==0)
        {
            while (n%p==0)
                n/=p;
            sol/=p;
            sol=sol*(p-1);
        }
        p+=2;
    }
    return sol;
}

int main()
{
    int n, s=0;
    in>>n;

    for (int i=1; i<=n; i++)
        s+=euler(i);

    out<<s*2-1;
    return 0;
}