#include <bits/stdc++.h>
int mod = 1000000007;
using namespace std;
int powmod(int64_t a, int64_t b) {
  int64_t ans = 1;
  while (b > 0) {
    if (b & 1) {
      b--;
      ans = (ans * a) % mod;
    } else {
      a = (a * a) % mod;
      b = b >> 1;
    }
  }
  return ans;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout << fixed;
  int n;
  cin >> n;
  if (n < 6) {
    cout << -1 << "\n";
  } else {
    cout << 1 << " " << 2 << "\n";
    cout << 1 << " " << 4 << "\n";
    cout << 1 << " " << 3 << "\n";
    for (int i = 5; i <= n; i++) {
      cout << 4 << " " << i << "\n";
    }
  }
  for (int i = 1; i < n; i++) {
    cout << i << " " << i + 1 << "\n";
  }
  return 0;
}
