#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
long long  n,a,b,r,phi[1000000],nr;
int main()
{
  f>>n;
  for (int i=1;i<=n;i++) phi[i]=i;
for (int i=2;i<=n;i++){
  if (phi[i]==i){
     for (int j=2*i;j<=n;j+=i) phi[j] /=i, phi[j] *= (i-1);
     phi[i]--;
  }
  g<<i<<" "<<phi[i]<<endl;
  a+=phi[i];
}
  g<<2*a+1;
  return 0;
}

// phi 4= 4(2-1)/2;  3-