#include <iostream>
#include <fstream>
#define N 1000005
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int n, e[N];
long long sol;

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

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

        out << 2 * sol + 1 << "\n";
        return 0;
}