#include <iostream>
#include <fstream>

using namespace std;
ifstream f("fractii.in");
ofstream l("fractii.out");
int i,j,phi[1000000],n;
long long s;


int main()
{
    f>>n;
    for (i=1;i<=n;i++)
    {
        phi[i]=i-1;
    }
    for (i=2;i<=n;i++)
    {
        for (j=2*i;j<=n;j=j+i)
        {
            phi[j]=phi[j]-phi[i];
        }
    }
    for (i=1;i<=n;i++)
    {
        s=s+phi[i];
    }
    l<<2*s+1;
    return 0;
}