#include <fstream>
#include <cmath>
using namespace std;

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

int phi(int k)
{
    int ret=1,div, nr;
    for(div=2; div<=k; div++)
    {
        nr = 0;
        while(k%div == 0)
            {nr++;k/=div;}
        if(nr)
            ret*=(div-1)*pow(div,nr-1);
    }
    return ret;
}

int n,s,i;
int main()
{
    in>>n;
    for(i=1; i<=n; i++)
        s+=2*phi(i);
    out<<s-1;
    return 0;
}