#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
using ii = pair<int, int>;
using vii = vector<pair<int, int>>;
void solve() {
  int n;
  cin >> n;
  if (n <= 5)
    cout << "-1\n";
  else if (n >= 6) {
    cout << "1 2\n1 3\n1 4\n2 5\n2 6\n";
    for (int i = 6; i < n; ++i) {
      cout << 2 << ' ' << i + 1 << '\n';
    }
  }
  for (int i = 0; i < n - 1; ++i) cout << i + 1 << ' ' << i + 2 << '\n';
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int tc = 1;
  while (tc--) solve();
}
