#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, n1;
  cin >> n;
  n1 = n;
  if (n < 6)
    cout << "-1" << endl;
  else {
    if (n == 6) {
      cout << "1 2" << endl
           << "2 3" << endl
           << "2 4" << endl
           << "3 5" << endl
           << "3 6" << endl;
    } else {
      cout << "1 2" << endl
           << "2 3" << endl
           << "2 4" << endl
           << "3 5" << endl
           << "3 6" << endl;
      n -= 6;
      int i = 7;
      while (n != 0) {
        cout << "2 " << i << endl;
        n -= 1;
        i += 1;
      }
    }
  }
  int i = 1;
  while (n1 != 1) {
    cout << i << " " << i + 1 << endl;
    n1 -= 1;
    i += 1;
  }
}
