#include<cstdio>

using namespace std;

#define INPUT "tije.in"
#define OUTPUT "tije.out"

FILE *fin = fopen(INPUT, "r"), *fout = fopen(OUTPUT, "w");

int N;

int main()
{
  fscanf(fin, "%d", &N);
  
  for(int i = N-1; i > 0; --i)
  {
    for(int j = N; j > 0; --j)
      for(int k = i; k > 0; --k)
        fprintf(fout, "%d %d\n", j, j+1);
    for(int j = i; j > 0; --j)
      fprintf(fout, "%d 1\n", N+1);
  }
  
  fclose(fin);
  fclose(fout);
  
  return 0;
}