#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5, inf = 1e9 + 7;
const long double eps = 1e-12;
const long long linf = (long long)1e18 + 7, mod = 1e9 + 7;
int main() {
  long long n;
  cin >> n;
  if (n < 6) {
    cout << "-1\n";
  } else {
    for (int i = 2; i <= n / 2 + 1; i++) {
      cout << "1 " << i << "\n";
    }
    for (int i = n / 2 + 2; i <= n; i++) {
      cout << "2 " << i << "\n";
    }
  }
  cout << "1 2\n";
  for (int i = 3; i <= n; i++) {
    cout << "2 " << i << "\n";
  }
  return 0;
}
