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