#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  if (n < 6) {
    cout << -1 << endl;
  } else {
    cout << "1 2\n1 3\n1 4\n4 5\n4 6" << endl;
    for (int i = 6; i < n; i++) {
      cout << "1 " << (i + 1) << "\n";
    }
  }
  for (int i = 1; i < n; i++) {
    cout << "1 " << (i + 1) << endl;
  }
  return 0;
}
