#include    <fstream>

using namespace std;

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

#define LL long long
#define VECTOR_MAX 100

LL n, counter;
LL v[VECTOR_MAX];

int main() {
    fin >> n;

    for (int i = 2; i <= n; i++)
        v[i] = i - 1;

    for (int i = 2; i <= n / 2; i++)
        for (int j = 2 * i; j <= n; j++)
            v[j] -= v[i];

    for (int i = 2; i <= n; i++)
        counter += v[i];

    fout << counter * 2 + 1;
}