#include <fstream>

using namespace std;

ifstream fi("fractii.in");
ofstream fo("fractii.out");


int main() {
  int n, i, j;
  long long suma = 0;

  fi >> n;
  int v[n];

  for (i = 1; i <= n; i++)
    v[i] = i - 1;
  for(i = 2 ; i <= n ; i++) {
    suma = suma + v[i];
    for(j = i * 2; j <= n; j += i)
      v[j] = v[j] - v[i];
  }
  fo << suma * 2 + 1;
  return 0;
}