#include <bits/stdc++.h>
using namespace std;
const long long int inf = 1LL << 62;
inline double ttime(double t) {
  double tt = ((double)t) / CLOCKS_PER_SEC;
  return tt;
}
long long int mn[100005];
void boost() {
  std::ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
}
int main() {
  boost();
  long long int n;
  cin >> n;
  if (n < 6) {
    cout << -1 << "\n";
    if (n == 2)
      cout << "1 2"
           << "\n";
    else if (n == 3) {
      cout << "1 2"
           << "\n";
      cout << "2 3"
           << "\n";
    } else if (n == 4) {
      cout << "1 2"
           << "\n";
      cout << "2 3"
           << "\n";
      cout << "2 4"
           << "\n";
    } else if (n == 5) {
      cout << "1 2"
           << "\n";
      for (long long int i = 0; i < (3); i++) cout << "2 " << (i + 3) << "\n";
    }
  } else {
    cout << "1 2"
         << "\n";
    cout << "2 3"
         << "\n";
    cout << "3 4"
         << "\n";
    for (long long int i = (5); i <= (n); i++)
      cout << i << " " << (i % 2) + 2 << "\n";
    cout << "1 2"
         << "\n";
    for (long long int i = 0; i < (n - 2); i++) cout << "2 " << (i + 3) << "\n";
  }
  return 0;
}
