#include <iostream>
#include <cmath>
#include <fstream>
using namespace std;

int n;

ifstream f("tija.in");
ofstream g("tija.out");
int main()
{
f>>n;
for(int i=1;i<=n-1;i++)
 {
  for(int j=n;j>=1;j--)
   {
    for(int z=1;z<=i;z++)
     g<<j<<" "<<j+1<<endl;
   }
  for(int z=1;z<=i;z++)
     g<<n+1<<" "<<"1"<<endl;
 }
}