#include <iostream>
#include <fstream>
using namespace std;

const char infile[] = "fractii.in";
const char outfile[] = "fractii.out";

ifstream in(infile);
ofstream out(outfile);

long a[1000000];
int main()
{
  int i,j;
  long long n, ct=0;
  in>>n;
  for(i=2;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];

  long long sum = 0;
  for(i=2;i<=n;i++)
    sum += a[i];
  out<<2*sum+1;

}