#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
void solve() {
  long long n;
  cin >> n;
  if (n < 6)
    cout << "-1" << endl;
  else {
    cout << "1 2\n2 3\n2 4\n1 5\n1 6\n";
    for (long long i = 7; i <= n; i++) {
      cout << 2 << " " << i << endl;
    }
  }
  cout << "1 2\n";
  for (long long i = 3; i <= n; i++) {
    cout << 2 << " " << i << endl;
  }
}
signed main() {
  long long t = 1;
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  while (t--) {
    solve();
  }
}
