#include <bits/stdc++.h>
using namespace std;
int N;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie();
  cin >> N;
  if (N <= 5)
    cout << -1 << "\n";
  else {
    cout << 1 << " " << 2 << "\n";
    cout << 2 << " " << 3 << "\n";
    cout << 2 << " " << 4 << "\n";
    cout << 3 << " " << 5 << "\n";
    cout << 3 << " " << 6 << "\n";
    for (int i = 7; i <= N; i++) cout << 3 << " " << i << "\n";
  }
  for (int i = 2; i <= N; i++) {
    cout << i - 1 << " " << i << "\n";
  }
  return 0;
}
