#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
void solve() {
  int n;
  scanf("%d", &n);
  if (n <= 5) {
    puts("-1");
  } else {
    n--;
    int x = ceil(1.0 * n / 2);
    for (int i = 1; i <= x; i++) {
      cout << "1"
           << " " << (i + 1) << endl;
    }
    for (int i = x + 1; i <= n; i++) {
      cout << "2"
           << " " << (i + 1) << endl;
    }
    n++;
  }
  int prev = 1;
  for (int i = 2; i <= n; i++) {
    cout << prev << " " << i << endl;
    prev = i;
  }
}
int main() {
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
