#include <fstream>

using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
double long sum;
int n,i,j,a[1000005];
int ;
int main()
{
    f>>n;
    a[1]=1;
    for (i=2; i<=n; i++)
    {
        a[i]=i-1;
    }
    for (i=2; i<=n; i++)
    {
        for (j=2*i; j<=n; j+=i)
        {
            a[j]-=a[i];
        }
    }
    for (i=1; i<=n; i++)
        sum+=a[i];
    g<<sum*2-1;
    return 0;
}