#include <fstream>

using namespace std;

ifstream cin("fractii.in");
ofstream cout("fractii.out");

int ind[1000009];

int main()
{
    int n;
    long long ans(0);
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        ind[i] = i - 1;
    }
    for (int i = 2; i <= n; ++i) {
        ans += 1LL * ind[i];
        for (int j = 2 * i; j <= n; j += i) {
            ind[j] -= ind[i];
        }
    }/// i/j si j/i + 1/1
    cout << ans * 2 + 1;
    return 0;
}