#include <iostream>
#include <fstream>

#define ll unsigned long long

using namespace std;

const int nmax = 1e6 + 5;

int euler[nmax];

int main()
{
    ifstream cin("fractii.in");
    ofstream cout("fractii.out");
    int n;
    ll s = 0;
    cin >> n;
    for (int i = 1; i <= n; i++) euler[i] = i - 1;
    for (int i = 2; i <= n; i++){
        for (int j = i * 2; j <= n; j += i)
            euler[j] -= euler[i];
        s += euler[i];
    }
    s = s * 2 + 1;
    cout << s;
    return 0;
}