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