#include <fstream>

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

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

int main() {
    int n, i, s = 0;
    cin >> n;
    for (i = 1; i <= n;i++){
        s += phi(i);
    }
    cout << 2*s-1;

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