#include <fstream>
#include <string>
#include <algorithm>
#include <stack>

using namespace std;

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

const int LMAX = 1e6 + 10;
int fr[LMAX];

int main()
{
    int n;
    cin >> n;
    for (int i = 2; i <= n; ++i) {
        fr[i] = i - 1;
    }
    long long ans = 0;
    for (int i = 2; i <= n; ++i) {
        ans = ans + 1LL * fr[i];
        for (int j = 2 * i; j <= n; j = j + i) {
            fr[j] = fr[j] - fr[i];
        }
    }
    ans = 2 * ans + 1;
    cout << ans;
    return 0;
}