#include <bits/stdc++.h>
const int mod = 1000000007;
const int N = 2e5 + 7;
using namespace std;
int a[N];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n, i, j, k, r, l, m;
  cin >> n;
  if (n < 6) {
    cout << "-1" << endl;
  } else {
    for (i = 2; i <= 4; i++) cout << "1 " << i << endl;
    for (i = 5; i <= n; i++) cout << "2 " << i << endl;
  }
  for (i = 2; i <= n; i++) cout << "1 " << i << endl;
  return 0;
}
