#include<stdio.h>

FILE *f=fopen("fractii.in", "r"), *g=fopen("fractii.out", "w");

long n;



long desc(int k)
{
 long d;
 float eul;
 int sem;
 d=2;
 eul=k;
 while(k!=1)
  {
   sem=0;
   while(k%d==0)
    {
     k=k/d;
     sem=1;
    }
   if(sem==1)
     eul=(float)eul*(1-(float)1/d);
   d++;
  }
 return eul;
}



int main()
{
 long s, rez, i;
 fscanf(f, "%ld", &n);
 fclose(f);
 s=0;
 for(i=2; i<=n; i++)
   s=s+2*desc(i);
 rez=s+1;
 fprintf(g, "%ld", rez);
 fclose(f);

 return 0;

}