#include <bits/stdc++.h>
using namespace std;
int n;
int main() {
  int i;
  cin.tie(0);
  cin.sync_with_stdio(0);
  cin >> n;
  if (n >= 6) {
    cout << 1 << " " << 2 << endl;
    cout << 1 << " " << 3 << endl;
    cout << 1 << " " << 4 << endl;
    cout << 2 << " " << 5 << endl;
    cout << 2 << " " << 6 << endl;
    for (i = 7; i <= n; i++) {
      cout << 2 << " " << i << endl;
    }
  } else {
    cout << -1 << endl;
  }
  for (i = 2; i <= n; i++) {
    cout << 1 << " " << i << endl;
  }
}
