#include <fstream>
#define DMAX 1000010

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

int n;
long long int sol;
int euler[DMAX];

int main() {
    fin >> n;
    for (int i = 2; i <= n; i++)
        euler[i] = i - 1;

    for (int i = 2; i <= n; i++) {
        sol += euler[i];
        for (int j = i << 1; j <= n; j += i)
            euler[j] -= euler[i];
    }

    fout << (sol << 1) + 1 << '\n';
    fout.close();
    return 0;
}