#include<iostream>
#include<fstream.h>
#include<stdio.h>
ifstream f("tije.in");
FILE *g=fopen("tije.out","w");
int main()
{
   int i,j,i1,n;
   f>>n;
   for(i=n-1;i;i--)
   {
     for(j=n;j;j--)
      for(i1=i;i1;i1--)
       fprintf(g,"%d %d\n",j,j+1);
      for(i1=i;i1;i1--)
       fprintf(g,"%d 1",n+1);
   }
   return 0;
}