#include <fstream>

using namespace std;

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

int phi(int n){
    int r = n, d=2;
    while (n>1) {
        while (n%d && d*d<=n)
            d++;
        if (d*d>n)
            d = n;
        r /= d;
        r *= d - 1;
        while (n%d==0) {
            n /= d;
        }
    }
    return r;
}

long long n, i, sphi;

int main() {
    cin >> n;
    for (i = 2; i <= n; i++) {
        sphi += phi(i);
    }

    cout << 2 * sphi + 1;

    cin.close();
    cout.close();
    return 0;
}