#include <iostream>
#include <fstream>
using namespace std;
int main()
{
  int n, i, j, a[100], sum = 0;
  ifstream f("fractii.in");
  ofstream g("fractii.out");
  f >> n;
  for (i = 1; i <= n; ++i)
    a[i] = i - 1;
  for (i = 2; i <= n; ++i)
    for (j = 2 * i; j <= n; j += i)
      a[j] -= a[i];
  for (i = 1; i <= n; i++)
    sum += a[i];
  g << 2 * sum + 1;
  f.close();
  g.close();
  return 0;
}