#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const int INF = 1e9;
const int N = 1e5 + 5;
void var1(int n) {
  for (int i = 2; i <= n; i++) cout << 1 << " " << i << endl;
}
void var2(int n) {
  if (n <= 5) {
    cout << -1 << endl;
    return;
  }
  for (int i = 2; i <= n - 2; i++) cout << 1 << " " << i << endl;
  cout << 2 << " " << n - 1 << endl;
  cout << 2 << " " << n << endl;
}
void solve() {
  int n;
  cin >> n;
  var2(n);
  var1(n);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie();
  cout.tie();
  int t = 1;
  while (t--) {
    solve();
  }
}
