#include <stdio.h>
#include <stdlib.h>
int n,i,j,nr;
int main()
{
    freopen("fractii.in", "r", stdin);
    freopen("fractii.out", "w", stdout);
    scanf("%d",&n);
    nr=2*n-1;
    for(i=2;i<n;i++)
    {
        for(j=i+1;j<=n;j++)
        {
            if(i%j!=0 && j%i!=0)
            {
                if((i%2==0 && j%2==0)||(i%3==0 && j%3==0))
                    nr+=0;
                else
                {
                    printf("\n%d/%d  %d/%d ",i,j,j,i);
                    nr+=2;
                }
            }
        }
    }
    printf("\n%d",nr);
    return 0;
}