#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n;
  cin >> n;
  if (n % 2 != 0) {
    if (n == 3 || n == 5)
      cout << "-1" << '\n';
    else {
      for (long long int i = 2; i < (n / 2) + 2; i++) {
        cout << "1 " << i << '\n';
      }
      for (long long int i = (n / 2) + 2; i < n + 1; i++) {
        cout << "2 " << i << '\n';
      }
    }
    for (long long int i = 2; i < n + 1; i++) {
      cout << "1 " << i << '\n';
    }
  }
  if (n % 2 == 0) {
    if (n == 2 || n == 4)
      cout << "-1" << '\n';
    else {
      for (long long int i = 2; i < (n / 2) + 2; i++) {
        cout << "1 " << i << '\n';
      }
      for (long long int i = (n / 2) + 2; i < n + 1; i++) {
        cout << "2 " << i << '\n';
      }
    }
    for (long long int i = 2; i < n + 1; i++) {
      cout << "1 " << i << '\n';
    }
  }
  return 0;
}
