#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  int n, i;
  cin >> n;
  if (n < 6)
    cout << -1 << endl;
  else {
    cout << 1 << " " << 2 << endl;
    for (i = 3; i <= n - 2; i++) cout << 2 << " " << i << endl;
    cout << 3 << " " << n - 1 << endl << 3 << " " << n << endl;
  }
  cout << 1 << " " << 2 << endl;
  if (n > 2) cout << 2 << " " << 3 << endl;
  if (n > 3) {
    for (i = 4; i <= n; i++) cout << 3 << " " << i << endl;
  }
  return 0;
}
