#include <fstream>

using namespace std;

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

const int N = 1000010;

int n, i, j, v[N];
unsigned long long x;

int main() {
    fin >> n;
    for (i = 2; i <= n; ++i) {
        v[i] = i - 1;
    }
    for (i = 2; i <= n; ++i) {
        x += v[i];
        for (j = i + i; j <= n; j += i) {
            v[j] -= v[i];
        }
    }
    fout << (x << 1) + 1;
}