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