#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  if (n < 6)
    cout << "-1" << endl;
  else {
    cout << "1 2" << endl;
    for (int i = 3; i < n + 1; i++) {
      if (i % 2)
        cout << "2 " << i << endl;
      else
        cout << "1 " << i << endl;
    }
  }
  cout << "1 2" << endl;
  for (int i = 3; i < n + 1; i++) {
    cout << i - 2 << ' ' << i << endl;
  }
  return 0;
}
