#include <fstream>

using namespace std;

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

int main()
{
    int prime[1000001], n;
    long long sol;

    cin >> n;
    for(int i = 1; i <= n; i++)
        prime[i] = i-1;

    for(int i = 1; i <= n; i++)
    {
        for(int j = 2 * i; i <= n; j += i)
            prime[j] -= prime[i];
        sol += prime[i];
    }
    cout << 1 + 2 * sol;
    return 0;
}