#include <fstream>

using namespace std;

ifstream cin("tije .in");
ofstream cout("tije.out");

int main()
{
    int n , i , j , h;

    cin >> n;

    for(i = 1 ; i <= n -1 ; i ++)
    {
      for (j = n ; j >= 1 ; j--)
      {
        for (h = 1  ; h <= i ; h++)
        {
          cout << j << " " << j+1 <<endl;
        }

      }
      for(h = 1 ; h <= i ; h++)
      {
        cout << n + 1 << " " << "1" << endl;
      }
    }

    return 0;
}