#include <stdio.h>

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