#include <bits/stdc++.h>
using namespace std;
const long long N = 1e6;
const long long mod = 1e9 + 7;
const long long INF = 10000000;
void flash() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout.setf(ios::fixed);
  cout.setf(ios::showpoint);
  cout.precision(9);
}
void bolt(long long n) {
  if (n <= 5) {
    cout << "-1\n";
    return;
  }
  long long bap = (n / 2) + (n % 2 >= 1);
  long long num = 2;
  for (long long i = 0; i < bap; i++) {
    cout << "1 " << (num++) << "\n";
  }
  for (long long i = bap; i < n - 1; i++) {
    cout << "2 " << (num++) << "\n";
  }
}
void yo(long long n) {
  long long num = 2;
  for (long long i = 0; i < n - 1; i++) {
    cout << "1 " << (num++) << "\n";
  }
}
void solve();
int32_t main() {
  flash();
  long long t;
  t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
void solve() {
  long long n;
  cin >> n;
  bolt(n);
  yo(n);
  return;
}
