#include<fstream.h>
#include<math.h>
ifstream f("fractii.in");
ofstream g("fractii.out");
unsigned long int n,i,j,k;
int prime(unsigned long int a,unsigned long int b)
{
    unsigned long int i ;
    if(a<b)
       for(i=2;i<=a;i++)
	  if(a%i==0&&b%i==0)
	     return 0;
    else
       for(i=2;i<=b;i++)
	  if(a%i==0&&b%i==0)
	     return 0;
    return 1;
}
int main()
{
   f>>n;
   k+=n;
   k+=n-1;
   for(i=2;i<=n;i++)
     for(j=i+1;j<=n;j++)
       if(prime(i,j))
       {
         g<<i<<"/"<<j<<endl;
	 k=k+2;
       }
   g<<k;
   return 0;
}