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