#include <fstream>
#define nmax 1000000

using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
unsigned long long N, nrFrc;
int v[nmax];
int suma(){
    int S = 0;
    for(unsigned i = 1; i <= N; ++i)
        S +=v[i];
    return S;
}
int main()
{unsigned i, j;
    f>>N;

    for (i = 1; i <= N; ++i) v[i] = i-1;

    for (i = 2; i <= N; ++i)
        for (j = 2 * i; j <= N; j += i)
            v[j] -= v[i];
        g<<2 * suma() + 1;
    return 0;
}