#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 4, M = 1e6 + 5, OO = 0x3f3f3f3f;
const long long mod = 1e9 + 7;
long long powmod(long long a, long long b) {
  long long res = 1;
  a %= mod;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
  }
  return res;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long lcm(long long a, long long b) { return a * b / gcd(a, b); }
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, ok = 1;
  cin >> n;
  if (n <= 5) {
    ok = 0;
    cout << "-1\n";
  }
  for (int i = 2; i <= n - 2 && ok; i++) cout << 1 << " " << i << endl;
  if (ok) {
    cout << 2 << " " << n - 1 << endl;
    cout << 2 << " " << n << endl;
  }
  for (int i = 2; i <= n; i++) cout << 1 << " " << i << endl;
  return 0;
}
