#include <bits/stdc++.h>
using namespace std;
long long const inf = 1e9;
long long const mod = 998244353;
long double const eps = 1e-9;
unordered_map<string, int> mapa;
int main() {
  int n;
  cin >> n;
  if (n <= 5)
    cout << -1 << endl;
  else {
    vector<int> l;
    vector<int> r;
    for (int i = (0); i < (n / 2); i++) {
      cout << 1 << ' ' << i + 2 << endl;
    }
    for (int i = (n / 2); i < (n - 1); i++) {
      cout << 2 << ' ' << i + 2 << endl;
    }
  }
  for (int i = (0); i < (n - 1); i++) {
    cout << i + 1 << ' ' << i + 2 << endl;
  }
}
