#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  if (n < 6)
    cout << -1 << '\n';
  else {
    cout << 1 << ' ' << 2 << '\n';
    cout << 2 << ' ' << 3 << '\n';
    cout << 2 << ' ' << 4 << '\n';
    cout << 3 << ' ' << 5 << '\n';
    cout << 3 << ' ' << 6 << '\n';
    for (long long i = 7; i < n + 1; ++i) {
      cout << 3 << ' ' << i << '\n';
    }
  }
  for (long long i = 1; i < n; ++i) {
    cout << i << ' ' << i + 1 << '\n';
  }
}
