#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x = 1;
  cin >> n;
  if (n < 6)
    cout << -1 << endl;
  else {
    for (int i = 2; i < 5; i++) cout << x << " " << i << endl;
    x = 4;
    for (int i = 5; i <= n; i++) cout << x << " " << i << endl;
  }
  x = 1;
  for (int i = 2; i <= n; i++) {
    cout << x << " " << i << endl;
    x = i;
  }
  return 0;
}
