#include <bits/stdc++.h>
using namespace std;
const long long int NUM = 2e5 + 5;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int num_tests = 1;
  while (num_tests-- > 0) {
    long long int n;
    cin >> n;
    vector<pair<long long int, long long int>> correct;
    correct.push_back({1, 2});
    for (long long int i = 3; i < n + 1; i++) {
      correct.push_back({2, i});
    }
    if (n < 6) {
      cout << -1 << "\n";
      for (auto x : correct) cout << x.first << " " << x.second << "\n";
      return 0;
    }
    vector<pair<long long int, long long int>> incorrect = {
        {1, 2}, {1, 3}, {1, 4}};
    for (long long int i = 5; i < n + 1; i++) {
      incorrect.push_back({4, i});
    }
    for (auto x : incorrect) cout << x.first << " " << x.second << "\n";
    for (auto x : correct) cout << x.first << " " << x.second << "\n";
  }
}
