#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  if ((n == 2 || n == 3) || (n == 4 || n == 5)) cout << -1 << endl;
  if (n != 2 && n != 3 && n != 4 && n != 5) {
    for (int g = 2; g <= n - 2; g++) cout << 1 << ' ' << g << endl;
    cout << 2 << ' ' << n - 1 << endl;
    cout << 2 << ' ' << n << endl;
  }
  for (int g = 2; g <= n; g++) cout << g - 1 << ' ' << g << endl;
}
