#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  int n;
  cin >> n;
  if (n <= 5)
    cout << -1 << endl;
  else {
    cout << 1 << ' ' << 2 << endl, cout << 1 << ' ' << 3 << endl,
        cout << 1 << ' ' << 4 << endl, cout << 4 << ' ' << n << endl,
        cout << 4 << ' ' << n - 1 << endl;
    int init = 4;
    while (init < n - 2) cout << init << ' ' << init + 1 << endl, init++;
  }
  for (int i = 1; i <= n - 1; i++) cout << i << ' ' << i + 1 << endl;
  return 0;
}
