#include <cstdio>
FILE *f = fopen("tije.in","rt"), *g = fopen("tije.out","wt");
long i,j,n,k;

int main()
{
 fscanf(f,"%ld\n",&n);
 for (i=n-1;i>=1;i--)
 {
  for (j=n;j>=1;j--)
   for (k=1;k<=i;k++)
    fprintf(g,"%ld %ld\n",j,j+1);
  for (k=1;k<=i;k++)
   fprintf(g,"%ld %ld\n",n+1,1);
 }
 fclose(f);
 fclose(g);
}