#include <iostream>
#include <fstream>
using namespace std;

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

int euler[1000001];

int main()
{
    int n;
    fin >> n;
    for (int i = 2; i <= n; ++i)
    {
        euler[i] = i - 1;
    }
    for (int i = 2; i <= n; ++i)
        for (int j = 2 * i; j <= n; j += i)
            euler[j] -= euler[i];
    long long s = 0;
    for (int i = 2; i <= n; ++i)
        {
            s += euler[i];
        }
    fout << s * 2 + 1;

    return 0;
}