#include <stdio.h>

int verifica(int a)
{int i,k=0;
 if(a!=2){
 for(i=2;i<=a/2;i++)
  {if(a%i == 0) k=1;}

  return k;}
  else return 1;
}

int main(void)
{long int n,prime=0,neprime=0,i,k=0;

    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);

  scanf("%ld",&n);
 for(i=1;i<=n;i++)
  {if(verifica(i)) neprime++;
		   else prime++;
    }

  for(i=1;i<=prime;i++)
   {k=k+n-1;}

  for(i=1;i<=neprime;i++)
   {k=k+prime;}

   printf("%ld",k+1);

 }