#include<iostream>
#include<fstream>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

int i,j,n,ct;

int main(){
	f>>n;
	ct=n;
	for(i=1;i<=n;i++)
	 	for(j=1;j<=n;j++)
	     {if(i==1&&j>=1)	
			if(i%j!=0)
			    {cout<<i<<" "<<j<<endl;
			     ct++;}
		 if(j>1&&i>1)
			if(i%j!=0&&j%i!=0)
				{cout<<i<<" "<<j<<endl;
				ct++;}}
				
	g<<ct;
return 0;}