#include <fstream>
using namespace std;

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

int n;
long long int sol;
int euler[1000010];

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 = 2 * i; j <= n; j += i)
            euler[j] -= euler[i];
    }
    fout << 2 * sol + 1 << '\n';
    return 0;
}