#include <fstream>
using namespace std;
int v[1000001], i, n, j;
long long s;
int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f >> n;
    for(i = 2; i <= n; i ++)
        v[i] = i - 1;
    for(i = 2; i <= n; i ++)
        for(j = 2 * i; j <= n; j = j + i)
           v[j] = v[j] - v[i];
    for(i = 2; i <= n; i ++)
        s = s + v[i];
    g << 2 * s + 1;
    return 0;
}