#include<fstream>
using namespace std;
long long a[1000001],n,s=0;
int i,j;
ifstream fin("fractii.in");
ofstream fout("fractii.out");

int main(){

  fin >> n;

  for (i=1; i<=n; i++)
      a[i]=i-1;
  for (i=2; i<=n; i++){
      s += a[i];
      for (j=2*i; j<=n; j+=i)
	  a[j] -= a[i];
  }

  fout << s*2+1;

 return 0;
}