#include <fstream>

using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

int phi[1000005];

int main()
{
    int n;
    fin >> n;

    phi[1] = 1;
    for(int i = 2; i <= n; ++i)
        phi[i] = i - 1;
    for(int i = 2; i <= n; ++i)
        for(int j = 2 * i; j <= n; j += i)
            phi[j] -= phi[i];

    unsigned long long rez = 0;
    for(int i = 1; i <= n; ++i)
        rez += phi[i];
    fout << 2 * rez - 1 << '\n';

    return 0;
}