#include <bits/stdc++.h>
using namespace std;
const int inf = 0x3f3f3f3f;
const int maxn = 1e5 + 5;
int read() {
  char c;
  bool flag = 0;
  c = getchar();
  while (!isdigit(c)) {
    if (c == '-') flag = 1;
    c = getchar();
  }
  int res = 0;
  do {
    res *= 10;
    res += c - '0';
    c = getchar();
  } while (isdigit(c));
  return flag ? -res : res;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  if (n < 6) {
    cout << -1 << endl;
  } else {
    cout << 1 << " " << 2 << endl;
    cout << 1 << " " << 3 << endl;
    cout << 1 << " " << 4 << endl;
    for (int i = 5; i <= n; i++) {
      cout << 4 << " " << i << endl;
    }
  }
  for (int i = 1; i < n; i++) {
    cout << i << " " << i + 1 << endl;
  }
  return 0;
}
