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