#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  if (n < 6)
    cout << -1 << "\n";
  else {
    cout << 1 << " " << 2 << "\n";
    cout << 1 << " " << 3 << "\n";
    cout << 1 << " " << 4 << "\n";
    for (int i = 5; i <= n; i++) {
      cout << 4 << " " << i << "\n";
    }
  }
  for (int i = 2; i <= n; i++) {
    cout << i - 1 << " " << i << "\n";
  }
}
