#include <bits/stdc++.h>
using namespace std;
inline void Boost() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
}
int main() {
  Boost();
  int n;
  cin >> n;
  if (n <= 5) {
    cout << "-1\n";
  } else {
    int next = 2;
    for (int i = 1; i <= n / 2; ++i, ++next) {
      cout << "1 " << next << "\n";
    }
    for (; next <= n; ++next) {
      cout << "2 " << next << "\n";
    }
  }
  for (int i = 2; i <= n; ++i) {
    cout << "1 " << i << "\n";
  }
  return 0;
}
