#include <bits/stdc++.h>
using namespace std;
const int MAX = (int)1e5 + 55;
const int INF = (int)1e9 + 77;
const int MOD = (int)1e9 + 7;
const double PI = 2 * acos(0.0);
const double EPS = 1e-7;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  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 << "1 " << i << '\n';
  return 0;
}
