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