#include<fstream.h>
 int prim(long n,long h){
     while(n!=h)
     if(n>h) n-=h;
     else
     if(n<h) h-=n;
     return h;
 }            
 int main(){
     ifstream f("fractii.in");
     ofstream g("fractii.out");
     long n,i,d=2;
     int x=0;
     long long s=0;
     f>>n;
     s+=n;
     i=1;
     while(d<=n){
         if(prim(i,d)==1) {s++;g<<i<<" "<<d<<"\n";}
         if(i==n) 
         {
         i=1;
         d++;
         }
         else
         i++;
     }
     g<<s<<"\n";
     g.close();
     return 0;
 }