#include <iostream.h>
#include <fstream.h>
   
    long n;
   
  void fract ()
   {
    long i,j;
           
        for ( i = 1; i <= N; ++i)
    v[i] = i-1;
for ( i = 2; i <= N; ++i)
    for ( j = 2*i; j <= N; j += i)
        v[j] -= v[i];
     }
        
     int main ()
  { 
    long long k=0;
    long i;
     fstream f("fractii.in",ios::in);
   fstream g("fractii.out",ios::out);
 f>>n;
     fract();
    for(i=2;i<=n;i++)
      {
        k=k+v[i];
        } 
     h=2*k+1;
    g<<h;
    return 0;
    }