#include <fstream>
#define NMax 1000005
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
long suma;
char vec[NMax];
int n;
int main()
{
    int i,j;
    f>>n;
    for (i=1;i<=n;++i)
        vec[i]=i-1;
    for (i=2;i<=n;++i)
        for (j=i+i;j<=n;j+=i)
            vec[j]-=vec[i];
    for (i=2;i<=n;++i)
        suma += vec[i];
    suma *= 2;
    g<<suma+1;
}