#include <bits/stdc++.h>
using namespace std;
int main() {
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  long long n;
  cin >> n;
  if (n <= 5) {
    cout << -1 << endl;
  } else {
    cout << 1 << " " << 2 << endl;
    for (int i = 3; i <= n; i++) {
      if (i % 2)
        cout << 1 << " " << i << endl;
      else
        cout << 2 << " " << i << endl;
    }
  }
  for (int i = 2; i <= n; i++) cout << 1 << " " << i << endl;
  return 0;
}
