#include <stdio.h>

int main()
{
	freopen("tije.in","r",stdin);
	freopen("tije.out","w",stdout);
         scanf("%d",&n);
         for(i=n-1;i>0;i--)
         {       for(j=n;j>0;j--)
                         for(k=i;k>0;k--)
                                 printf("%d %d\n",j,j+1);
                 for(j=i;j>0;j--)
                         printf("%d 1\n",n+1);
         }
         return 0;

}