#include <fstream>
using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n, i, j, v[1000010];
long long int ans;

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

    for (i = 2 ; i <= n / 2 ; i++) {
        ans += v[i];
        for (j = 2 * i ; j <= n ; j += i) {
            v[j] -= v[i];
        }
    }

    for (; i <= n ; i++)
        ans += v[i];
    ans *= 2;
    ans ++;

    fout << ans;
}