#include<stdio.h>

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


long n;


int prim(long i)
{
 long d=2;
 while(d*d<=i)
  {
   if(i%d==0)
     return 0;
   d++;
  }
 return 1;
}


void generare()
{
 long i, d, aux;
 long s;
 s=n*n-n+1;
 for(i=2; i<=n; i++)
  if(prim(i)==1)
    {
     d=1;
     aux=i;
     while(aux<=n)
      {
       d++;
       aux=i*d;
      }
     s=s-(d-1)*(d-2);
    }
 fprintf(g, "%ld", s);
}


int main()
{
 fscanf(f, "%ld", &n);
 generare();
 fclose(f);
 fclose(g);

 return 0;

}