#include <bits/stdc++.h>
using namespace std;
long long n;
signed main() {
  cin >> n;
  if (n <= 5)
    cout << -1 << endl;
  else {
    for (long long i = 2; i <= n - 2; i++) cout << 1 << ' ' << i << endl;
    cout << 2 << ' ' << n - 1 << endl;
    cout << 2 << ' ' << n << endl;
  }
  for (long long i = 1; i < n; i++) cout << i << ' ' << i + 1 << endl;
  return 0;
}
