#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n, phi[1000005];
long long total;

int main() {
    fin >> n;
    for (int i = 1; i <= n; ++i)
        phi[i] = i - 1;
    for (int i = 2; i <= n; ++i) {
        total += phi[i];
        for (int j = i * 2; j <= n; j += i)
            phi[j] -= phi[i];
    }
    fout << total * 2 + 1;
    return 0;
}