#include <iostream>
#include <cmath>
#include <fstream>
using namespace std;
unsigned long long fct(unsigned long long n)
     {
       unsigned long long result = n;
       for(unsigned long long i=2;i*i <= n;i++)
       {
         if (n % i == 0) result -= result / i;
         while (n % i == 0) n /= i;
       }
       if (n > 1) result -= result / n;
       return result;
     }
bool prim(unsigned long long x)
{
    for(unsigned long long d=2;d<=sqrt(x);d++)
        if(x%d==0)
        return 0;
    return 1;
}
int main()
{
    unsigned long long n,nr=1;
    ifstream fin("fractii.in");
    fin>>n;
    ofstream fout("fractii.out");
    nr+=2*(n-1);
    for(unsigned long long a=2;a<n;a++)
    {
        long double x=0;
        x=(n-a+1)*1.0*fct(a)/a;
        x=floor(x);
        nr+=2*x;
    }
    fout<<nr;
    cout<<nr;
}