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