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