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