#include <stdio.h>
int i,j,k,n;
int main()
{
 FILE*g=fopen("tije.out","w");
 FILE*f=fopen("tije.in","r");
 fscanf(f,"%d",&n);
 for (i=1; i<=n-1; i++)
   fprintf(g,"%d %d\n",1,n+1);
 for (i=2; i<=n; i++)
   {
    fprintf(g,"%d %d\n",i,1);
    fprintf(g,"%d %d\n",n+1,i); }
 for (i=2; i<=n-1; i++)
   {
    for (k=n+1; k>=3; k--)
      for (j=1; j<=i; j++)
        fprintf(g,"%d %d\n",k-1,k);
    for (j=1; j<=i; j++)
      fprintf(g,"%d %d\n",n+1,2); 
   }
 return 0;
}