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