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