#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, n1;
  cin >> n;
  n1 = n;
  if (n < 6)
    cout << -1 << endl;
  else {
    cout << "1 2" << endl;
    cout << "1 3" << endl;
    cout << "1 4" << endl;
    n -= 4;
    for (int j = 5; j < 5 + n; j++) {
      cout << "2 " << j << endl;
    }
  }
  for (int i = 1; i < n1; i++) cout << i << " " << i + 1 << endl;
  return 0;
}
