#include <fstream>

using namespace std;

int i, j, t;
int main(){

  ifstream fin ("tije.in");
  ofstream fout ("tije.out");

  int n;
  fin >> n;

  for (i = n - 1; i >= 1; i--){
    for (j = n; j >= 1; j--)
      for (t = 1; t <= i; t++)
        fout << j << " " << j + 1 << "\n";
    for (int t = 1; t <= i; t++)
      fout << n + 1 << " " << 1 << "\n";
  }
  return 0;
}